The practice case Arthur D. Little publishes on its careers site is about a budget gym chain. Not a telecom operator, not a specialty chemicals plant, not a hydrogen electrolyzer. The firm's own case interview page says the case is used "to assess your ability as a consultant and not to test your business sense or sector knowledge."
The candidates who write to me about ADL have usually spent the week before the interview reading about 5G spectrum and battery chemistry. That is the wrong week. What ADL publishes is a mechanics test in four stations: a structure with at least two layers, arithmetic on numbers the interviewer hands you, a structured brainstorm, and a close you are expected to defend. Sector reading has a place, and it is the behavioral interview.
Below: what the firm states, what candidates report, and a four-station case to time yourself against.
What ADL puts in writing, and what it does not
ADL's careers site has interview-preparation pages for the case interview, the practice case study, and the behavioral interview. Five tips, one case, six example questions. That is more than most firms its size publish and less than prep sites pretend.
| What you will read | Status |
|---|---|
| "At least two layers" of structure; think out loud; "defend the side you choose" | Stated on the ADL case interview page |
| The case does not test sector knowledge | Stated on the ADL case interview page |
| Two to three rounds; consultants first, principals or partners last | Candidate reports, consistent; not on any ADL page |
| Written or presentation case in some offices, more often for experienced hires | Candidate reports, office-dependent; not on any ADL page |
| Candidate-led or interviewer-led | Prep sites disagree; the firm is silent |
One wrinkle: the behavioral page says the case tests "your business sense and approach to problem-solving"; the case page says it is "not to test your business sense." Both agree it is not about sector knowledge. And no ADL page mentions a written case, a phone screen that turns into a market sizing, or an online test. Those come from candidate reports, vary by office, and your invitation email outranks every blog, including this one.
A firm of 1,700 people hires office by office
Office matters more at ADL than at a firm ten times its size. The 2024 Sustainability Report puts "~2k employees" in its opening infographic and 1,704 in the GRI table at the back, across 51 offices in 39 countries: about 33 people per office. At that scale, expect recruiting to run office by office rather than through one central pipeline. The same report lists 402 new hires in 2024 by region:
| Region | 2024 hires | Share |
|---|---|---|
| Middle East and India | 176 | 44% |
| Europe | 118 | 29% |
| Asia | 83 | 21% |
| Americas | 17 | 4% |
| Africa | 2 | under 1% |
The regions sum to 396 against a stated 402; the report notes small differences in data-gathering methods. The point survives: the modal ADL hire in 2024 was in the Middle East and India region, and the Americas took 17 people all year. A written case reported in one city and absent in another is not a contradiction. It is two offices.
The four stations of the published case
ADL's practice case is four exercises, each introduced by the interviewer. A European high-end gym chain is weighing a budget brand. Station one: a structure. Station two: a city of 5 million, a €300 million market, a 25% share ambition, a €210 million revenue requirement, €360 a year per member, and the question of what share of non-members must join. Station three: the CEO asks for other revenue streams. Station four: the same CEO, now in a hurry, wants findings and next steps. Candidate reports describe live cases with the same arc.
| Station | ADL's own instruction | What the interviewer is listening for | Where points leak |
|---|---|---|---|
| Structure | "At least two layers"; pause for questions | A second layer that names an analysis, not a category | Four buckets with nothing underneath |
| Quant | Drop the zeros; steer the interviewer through "the intermediate steps" | The question restated before the first multiplication | Perfect arithmetic on a neighboring question |
| Brainstorm | "Three distinct groups (or two, if that's not possible)" | Groups first, ideas second, one you would actually test | Nine ideas, no groups, no favorite |
| Close | Five points: structured, concise, next steps, decisive, backed by facts | The number from station two, reused | "It depends" |
The two-layer requirement is the most concrete thing any firm publishes about structures, and most candidates still miss it. "Customers, competition, economics, operations" is one layer. The second is what you would do under each: "customers: how many people in the city have no gym membership, and what would move them." If a second-layer item cannot be turned into a question to the interviewer, it is not a second layer.
Who leads is the wrong question
Prep sites split on whether ADL cases are candidate-led or interviewer-led; the firm does not say. The published case suggests the split is false. The interviewer moves you between stations; you drive inside each one. When the interviewer says "let's focus on one of the cities," the station has changed, and the worst thing you can do is keep talking about your framework.
Practice both gears, then the gear change. The interviewer-led versus candidate-led guide covers the general mechanics. The ADL habit is smaller.
Ned's rule. New numbers mean a new station. Before you multiply anything, say the question back in one sentence and name the unit of the answer. Most quant failures I have scored were reading failures with arithmetic attached.
ADL's own numbers show why. Twenty-five percent of a €300 million market is €75 million, not €210 million. The figures reconcile only once you ask what the 25% is a share of and whether €210 million is the brand's total or the city's. No answer key is published. I suspect that is deliberate: the tips beside the numbers say to ask clarifying questions.
A four-station case you can time yourself against
Invented company, invented numbers, ADL shape. Give yourself 25 minutes.
Prompt. Lindqvist Buss runs 400 diesel buses for a Swedish regional transport authority under an eight-year contract paid per kilometer. The next contract, 2028 to 2036, will require zero-emission buses. The CEO asks: should we bid, and at what price?
Station one, structure (four minutes). Two layers, aloud:
- Economics of the switch: capex premium per bus and for depots; operating cost per kilometer, energy and maintenance; resale value after eight years.
- Contract: the price per kilometer the authority will accept; reliability penalties; whether the authority funds depots.
- Operations: route lengths against range; depot grid connection; retraining drivers and mechanics.
- Alternatives: do not bid and shrink; bid with a leasing partner who owns the buses; a smaller mixed fleet.
Open economics first: if the numbers fail over eight years, nothing else matters.
Station two, quant (eight minutes). The interviewer says, "Let's focus on the economics." You restate: "How much must the price per kilometer rise for an electric bid to match diesel over the contract? The answer is in euros per kilometer." You will not know the inputs; you are not supposed to. You ask, and receive:
| Input | Value |
|---|---|
| Buses | 400 |
| Kilometers per bus per year | 60,000 |
| Diesel bus price | €300,000 |
| Electric bus price | €500,000 |
| Diesel energy | 0.4 liters per km at €1.50 per liter |
| Electric energy | 1.2 kWh per km at €0.20 per kWh |
| Maintenance saving, electric | €0.06 per km |
| Depot charging, one-off | €15 million |
Work it in the order you would say it:
- Fleet kilometers: 400 × 60,000 = 24 million km a year.
- Capex premium: €200,000 × 400 = €80 million.
- Energy per km: diesel €0.60, electric €0.24, saving €0.36. Add €0.06 of maintenance: €0.42 per km.
- Annual saving: €0.42 × 24 million = €10.08 million.
- Payback on the premium: 80 ÷ 10.08 ≈ 7.9 years, the length of the contract, with no resale value assumed.
- The depots do not pay back. €15 million over eight years is €1.875 million a year, or about €0.078 per km over 24 million km.
Answer: about 8 cents per kilometer above the diesel price, ignoring financing and resale value. If Lindqvist bills around €3.00 per kilometer today, that is a rise of roughly 2.6%. Sanity-check aloud: €0.36 per km on 60,000 km is €21,600 per bus per year in energy alone, a saving you can defend.
Station three, brainstorm (four minutes). "The CEO wants other ways to close the 8 cents." Groups first:
- Cut the capex: lease the buses; battery-as-a-service; ask the authority to fund depots, since it set the rule.
- Raise the value: a resale-value guarantee from the manufacturer; overnight depot charging sold to a logistics firm; depot cost spread across a neighboring contract.
- Cut the risk: index the price to electricity costs; demand an uptime guarantee.
Pick one: the resale guarantee. A bus worth €100,000 after eight years is 400 × €100,000 = €40 million, which covers the depots more than twice over.
Station four, close (two minutes). "Bid, at roughly 8 cents per kilometer above today's price, about 3%. The €80 million fleet premium pays back within the contract from a 42-cent saving per kilometer; the €15 million of depots does not, and that is what the increase covers. Next steps: confirm whether the authority will fund depots, and get a manufacturer quote with a resale-value guarantee, which could remove the increase entirely. Main risk is the electricity price, so we ask for indexation." Forty seconds, every number from station two.
Scoring the same case twice
Same case, two candidates: one gets the arithmetic right and skips the mechanics ADL names; the other does what the pages say. Five-point scale per skill, which is common; ADL does not publish its own.
| Station | Weak answer | Score | Strong answer | Score |
|---|---|---|---|---|
| Structure | "Costs, revenues, operations, risks," then waits | 2 | Four branches with named analyses, opens economics first with a reason | 4 |
| Quant | Computes the €10.08 million saving, stops, says "so it's profitable" | 2 | Restates the question, reaches €0.078 per km, sanity-checks per bus | 5 |
| Brainstorm | Seven ideas in the order they arrived | 2 | Three groups, eight ideas, picks one and sizes it at €40 million | 4 |
| Close | "It depends on the authority's price" | 1 | Decision, number, two next steps, one risk, in 40 seconds | 5 |
The weak candidate is not bad at math. Every figure is right. The sheet still reads 7 out of 20: no second layer to score, a quant answer to a question nobody asked, a recommendation never made. The strong candidate scores 18 with the same arithmetic. That gap is ADL's published advice, applied.
Where the sector reading belongs
ADL's behavioral page tells you to "stay up to date with the most important economic events" because "we may want to check your current knowledge level," and one of its six example questions is "What company do you think is having a tough time now, and what would you recommend they do?" That is where your reading goes. Pick one company you can explain in 90 seconds, ideally outside your interviewer's sector, where they know more than you. Prepare a structure, one number, and a recommendation you would defend. It is a mini-case with no data.
Read what ADL partners write. Prism, the firm's magazine, publishes long-form pieces across the sectors the firm lists in its report, from automotive and energy to telecoms, healthcare, and travel. Two articles from your interviewer's practice, read properly, beat a week of industry primers. Your case may come from any sector. Your ability to solve it will not.
For "why us," skip "world's first consulting firm"; it is on every ADL page, and the interviewer has read it more often than you have. The firm's timeline has the 1886 founding in Boston and the 140th anniversary in 2026. The fact fewer candidates use is the management buyout of 30 December 2011 that made ADL partner-owned again under Ignacio Garcia-Alves, CEO since. Say why partner ownership changes a firm's incentives and you have said something.
Practice this today
One assignment: run the four stations on an unseen case against a clock. Structure in four minutes, two layers aloud. Quant with the question restated first. Brainstorm in groups. Close in under a minute with a number in it.
Use CoachNed's structure drill for station one and refuse to submit anything with a single layer; the math drill and brainstorming drill cover stations two and three, and the synthesis drill is station four on repeat. For the full arc out loud, the live case with Ned runs about 18 minutes and debriefs on seven scores. The behavioral simulator pushes four follow-ups into your "company in trouble" answer. Everything is open for seven days with no card; after that it is $120 for a recruiting season or $49 a month.
CoachNed is independent and not affiliated with Arthur D. Little. Its cases are AI-simulated originals; ADL's own practice case is the one piece of homework I would not skip.
Frequently asked questions
Is the Arthur D. Little case interview candidate-led or interviewer-led?
The firm does not say, and prep sites disagree. Its published practice case is four interviewer-introduced exercises in which the candidate drives the structure, calculation, brainstorm, and close. Drive within a station; stop when the interviewer opens the next one.
Does ADL use a written case or presentation?
Not on any of the firm's interview-preparation pages. Candidates in some offices, more often experienced hires, report a packet-and-slides exercise with about an hour of preparation on site or up to two days if sent ahead. Treat it as office-specific and ask your recruiter.
How many interview rounds does Arthur D. Little have?
Candidate reports consistently describe two to three: a first round with consultants or managers running one or two cases plus light fit, and a final round with principals or partners and more behavioral weight. The firm's pages describe the components, not the count.
Do I need engineering or technology knowledge for an ADL case?
The firm's case interview page states the case is "not to test your business sense or sector knowledge," and its published practice case is a gym chain. Sector reading helps in the behavioral interview, where ADL says it may check your awareness of current economic events.
Sources
- Case Interview | Arthur D. Little — five tips, "at least two layers," and the statement that the case does not test business sense or sector knowledge. Checked 2026-09-24.
- Case Study | Arthur D. Little — the published practice case, its four exercises, the quant figures quoted, and the five-point close. Checked 2026-09-24.
- Behavioral Interview | Arthur D. Little — six example questions, the "economic events" tip, and the page's description of the case as testing business sense. Checked 2026-09-24.
- ADL 2024 Sustainability Report (PDF) — 51 offices in 39 countries, "~2k employees," 1,704 headcount, 402 new hires by region, and the sector list. Checked 2026-09-24.
- Timeline | Arthur D. Little — 1886 founding in Boston, the 2011 buyout, and the 140th anniversary in 2026. Checked 2026-09-24.
- Arthur D. Little publishes special 135th anniversary edition of Prism magazine — buyout completed 30 December 2011; Ignacio Garcia-Alves led it and has been CEO since. Checked 2026-09-24.
- Prism - Arthur D. Little — the firm's magazine, cited as reading for the behavioral interview. Checked 2026-09-24.