PartnerRound- 01SituationTwo sentences of context
- 02TaskYour goal and what was at stake
- 03ActionMost of your time: what you did
- 04ResultNumbers, what changed, what you learnt
By the end you can
- Explain what each firm's experience questions test and what a strong answer has to show
- Tell a story in STAR form in under three minutes, with most of it on your own actions
- Build a bank of 6 to 10 stories mapped to the qualities McKinsey assesses
- Hold up under five layers of follow-up questions on one story without running out of detail
On this page
01What the fit interview tests
The case tests how you think. The fit interview tests whether the firm would put you in front of a client, trust you with a team and want to work beside you at midnight before a deadline. Don't treat it as a warm-up: a weak experience answer can undo strong case work.
- Impact: you've made something happen that wouldn't have happened without you.
- Leadership and teamwork: you can get people who don't report to you to move.
- Drive: you set yourself hard goals and keep going when things go wrong.
- Self-awareness: you know what you did well, what you'd change and why.
- Motivation: you know what consulting involves and why you want it.
Formats vary by office, role and round, so ask your recruiter what to expect. The preparation below covers all three firms: a story that survives McKinsey's follow-ups will be more than enough elsewhere.
02The McKinsey PEI: one story, in depth
In the PEI the interviewer asks for one experience, for example 'Tell me about a time you changed the mind of someone who disagreed with you', then spends most of the slot drilling into it. They aren't after a polished narrative. They want what you did, why you did it and how others reacted, in enough detail that it couldn't have been made up.
Each interviewer usually focuses on one dimension, so across a round you'll cover several. Candidates commonly report staying on a single story for ten minutes or more.
03STAR, adapted for consulting
STAR (Situation, Task, Action, Result) is the right skeleton. The consulting adaptation is about weight. Most candidates spend half their time setting the scene; interviewers want most of it on Action, and on your own part in it.
Say 'I' when you mean I. 'We redesigned the process' tells the interviewer nothing about you. 'I proposed the redesign, the senior picker and I wrote the new lists, and the manager chose the pilot shift' does.
Keep the opening telling to two or three minutes, then stop. The interviewer will steer, and a five-minute monologue spends the time they wanted for questions.
Check yourself
In the opening telling of a PEI story, which part of STAR should take most of your time?
04Build a story bank of 6 to 10 stories
You need more stories than you think. Two interviewers in a round may ask about the same dimension, and you'll want a fresh story for the second. Aim for 6 to 10 stories, with at least two strong ones for each dimension. One story can cover two dimensions, but try not to tell the same one twice in a round.
- Write each story as bullet points, never a script. Scripts sound recited and fall apart at the first follow-up.
- Note the numbers: sizes, dates, before and after.
- Name the people by role and know what each of them wanted.
- Write down the one thing you'd do differently, and mean it.
- Prefer recent stories. The last two or three years beat school, unless the school story is exceptional.
05The follow-up ladder
After your opening, the interviewer climbs a ladder of questions, each rung deeper into your thinking. Candidates with rehearsed stories are fine on the first rung and run dry by the third.
- 01FactsWhat happened? Who was involved?
- 02Your actionsWhat exactly did you do?
- 03ReasonsWhy that, and not something else?
- 04OthersHow did they react? What did you say?
- 05ReflectionWhat would you do differently?
Prepare by having a friend run the ladder on each story, asking 'why?' and 'what did you say?' until you can't answer. Wherever you stall is the detail to recall and write down.
- What were your options, and why did you pick that one?
- What did you say to them, word for word?
- What did they think of you at that point?
- What was the hardest moment, and how did you feel?
- What would have happened if you hadn't stepped in?
- How do you know the result was down to you?
Weak
I explained the data and why the change made sense, and in the end he agreed it was worth trying.
Strong
I said: 'I think I got this wrong. Before I suggest anything else, could I spend two shifts on the floor and learn how picking actually works?' He looked surprised, then told me to be there at 4am on Monday. That conversation mattered more than the analysis.
Why: The interviewer asked for words, so give words. The strong answer is specific enough to be clearly real, shows the candidate changing approach, and reveals judgement. The weak answer could describe any project and suggests the candidate doesn't remember, or wasn't really there.
Check yourself
The interviewer asks 'Why did you choose that approach?' What should a strong answer include?
06Worked example: a personal impact story
Worked example
'Tell me about a time you changed someone's mind'
Situation
Eighteen months into my first job, I was an operations analyst at a food wholesaler that delivers to about 400 restaurants. In our biggest depot, 18% of the 2,400 deliveries a week arrived late, against a 5% target, and two restaurant groups had warned us they might leave.
Task
My manager asked me to find out why and fix it. The catch: any change on the floor was the depot manager's call. He'd run the depot for 20 years, didn't report to my manager, and was tired of head-office projects.
Action
- I analysed three months of scan data and found the delay wasn't the drivers. Orders were picked in the order they arrived, not in van order, so the last vans waited for items scattered across the warehouse.
- I sent the depot manager a deck proposing pick lists sorted by van. He rejected it in one line. That was my mistake: I'd built a solution without understanding his floor.
- I asked to work two early shifts with the pickers, and found the real objection. Pickers earned a bonus on picks per hour, and picking in van order would cut it.
- I redesigned the proposal with the senior picker. We kept the picks-per-hour measure but added a bonus for every van loaded on time. I took it to my manager and HR, who approved it for a two-week pilot.
- I asked the depot manager to choose the pilot shift and run it himself, with the other shift carrying on as before for comparison, and a 10-minute review each morning.
Result
On the pilot shift, late deliveries fell from 18% to 7% in two weeks, while the other shift stayed at 18%. The depot manager rolled it out to both shifts himself and presented it to the regional director. Across the depot that's about 264 fewer late deliveries a week (432 down to 168), roughly $275k a year in late-delivery credits at $20 each, and both restaurant groups stayed.
We're still above the 5% target; the rest is a driver shortage, a separate problem. What I learnt: I tried to win the argument with data before I understood the objection.
The follow-ups, with strong answers
Why do you think your first proposal failed? I treated it as an analysis problem. He'd seen head-office tools come and go, and my deck asked him to trust a model built by someone who'd never seen his floor at 4am. It also ignored the bonus, which was what his team cared about most.
Did you have the authority to change the bonus? No. I took the proposal to my manager and our HR partner with the numbers: on the pilot's assumptions, total bonus cost stayed about the same. They approved it for two weeks only, which also made it easier for the depot manager to say yes.
How did you get the pickers on board? Through the senior picker. She'd been there 12 years and the others followed her lead, so I asked her to veto any change that made the job harder. She vetoed two, and both were mine.
How do you know the improvement came from your change? The other shift ran the old way over the same two weeks, on the same routes, and stayed at 18%. It isn't a perfect experiment, but it was enough for the depot manager to trust it, and the depot held at about 7% after the rollout.
What would you do differently? Go to the floor first. The deck cost me three weeks and some goodwill. Now, on any new problem, I talk to the people who do the work before I build the model.
What did the depot manager think of you by the end? He asked my manager to send me to the next depot project. That was the result I was proudest of.
Notice what makes it work: a setback in the middle, a named person who resisted, the candidate's own decisions at every step, numbers that tie out and an honest lesson. It is not a story where everything went right.
07Why consulting? Why this firm?
Expect one or both, often at the start. A good answer has three parts: what draws you to the work, evidence from your past that it suits you, and what you want to learn. Keep it under a minute.
'Why this firm?' must be specific to that firm, or it isn't an answer. Name a conversation, a practice or a way of working you've checked, and link it to your own story.
Never give exit opportunities as your main reason. It may be true, but it tells the interviewer you're already planning to leave.
08Red flags that sink strong cases
- No resistance. If nobody disagreed and nothing went wrong, it isn't a story about impact or leadership.
- A recited script. A word-perfect opening that collapses at the first follow-up sounds rehearsed, not lived.
- Blaming others. Criticising a former boss or teammate to make yourself look better.
- Taking all the credit. The opposite failure: no acknowledgement of anyone who helped.
- Fuzzy numbers. Not knowing the size of the team, the budget or the result.
- No reflection. Answering 'what would you do differently?' with 'nothing'.
- Stretching the truth. Interviewers probe until the detail runs out. Embellishment is easy to spot and hard to recover from.
- A thin 'why consulting'. Prestige, money or exit options as the main reason.
Check yourself
Which of these is the weakest choice for a PEI story on personal impact?
Cheat sheet
The lines worth rereading the night before.
- 1The fit interview is assessed, not a warm-up. A weak story can undo strong cases.
- 2The McKinsey PEI is one story, probed in depth, often for ten minutes or more. Prepare for depth, not breadth.
- 3Dimensions as commonly described: personal impact, entrepreneurial drive, inclusive leadership, courageous change. Check your invitation for the current names.
- 4STAR with the weight on Action: about 60% of the telling on what you did and why. Say 'I'.
- 5Bank 6 to 10 recent stories, at least two per dimension, written as bullets, not scripts.
- 6Every strong story has stakes, resistance, your decisions, numbers and an honest lesson.
- 7Practise the ladder: facts, your actions, your reasons, others' reactions, reflection.
- 8Why consulting: the work, evidence it suits you, what you want to learn. Why this firm: specifics only.
Read the full guide
The same ground on the blog, with more worked examples and practice on the page.
Questions candidates ask
What is the McKinsey PEI?
The Personal Experience Interview: the part of a McKinsey interview where you describe one experience and the interviewer probes it in depth. Each interviewer usually focuses on one quality, such as personal impact or leadership. Expect detailed follow-ups on what you did, why, and how others reacted.
How many stories should I prepare for the PEI?
Six to ten, with at least two strong stories for each dimension. More than one interviewer may ask about the same dimension, and a fresh story beats a repeat. One story can cover two dimensions if it's rich enough.
Can I use stories from university or outside work?
Yes, if the stakes were real and your role was substantial. Societies, sport, volunteering and part-time jobs all work. Recent stories are better, and stories where you influenced people senior to you or outside your control are especially useful.
Do BCG and Bain have a PEI?
The PEI is McKinsey's format. BCG and Bain ask about your experience and motivation too, usually with less structured follow-up, and formats vary by office. A story prepared to PEI depth works for all three.
How long should my answer to a PEI question be?
Aim for two to three minutes for the opening telling, then let the interviewer steer. They want time for follow-ups, and a long monologue tends to bury your actions in context.