What Is an Assessment and Development Centre? A Guide for HR Leaders

Most promotion decisions still rest on a manager’s impression of someone they already like working with. That impression is shaped by proximity, similarity and recency far more than by capability. A centre exists to interrupt that, by putting several people through identical tasks in front of several trained observers, then comparing what they actually did. This guide covers how centres work, the difference between assessment and development, what they measure, and when they are worth the investment.

What is the difference between an assessment centre and a development centre?

The difference is purpose, not method. An assessment centre produces a decision, usually about selection, promotion or succession. A development centre produces a plan, and the participant owns their own results. The exercises can be identical. What changes is who sees the output and what happens next.

This distinction matters more than most organisations realise. Participants behave differently when they know a result affects their promotion prospects, and they will manage their impression accordingly: research on assessment centres finds that candidates use impression management behaviours such as self-promotion and ingratiation, and that these relate to their ratings [Source: Klehe and colleagues 2014]. In our experience, in a genuine development centre, where results are confidential to the individual and their coach, people take more risks and the data is often more honest. Our assessment and development centres are designed around which of the two outcomes you actually need.

How does an assessment centre work?

A centre typically runs from one to three days depending on the number of participants and puts them through several custom-built exercises that simulate the real demands of the target role. The centre can be run face-to-face or virtually. Typical components include a group discussion, a role play with a trained actor, an in-tray or inbox exercise, a case analysis with presentation, and a structured interview. Each exercise is scored independently by different assessors.

The design principle is simple. No single exercise is trusted on its own. Each competency is observed in at least two different situations by at least two different assessors, and the scores are reconciled in a calibration session. This approach helps ensure that conclusions are based on multiple sources of evidence rather than a single observation.

Often, assessment centres include psychometric testing, typically personality and cognitive ability assessments, which help inform an individual’s potential to succeed in specific roles. When considered alongside observed performance, these assessments provide valuable insights and contribute to a more comprehensive understanding of capability.

What competencies should a centre measure?

A centre should measure only the behaviours that genuinely differentiate performance in the target role, typically following a job analysis exercise. There is usually a trade-off when deciding how many competencies to assess. Too many competencies may require additional assessment instruments, increasing the length and cost of the centre. Too few may result in insufficient evidence to evaluate all competencies that are critical to success in the role.

We anchor centre design in a leadership competency framework built on three clusters: self-leadership, people leadership and business leadership. Where an organisation already has its own framework, we map the exercises to it rather than imposing ours. Our wider organisational transformation work includes competency framework design for organisations that do not yet have one.

Why do assessment centres fail?

Assessment centre design is grounded in scientific research and requires specialised expertise, often from organisational psychologists. Multiple factors can undermine the quality of a centre, including a design that is not fit for purpose, insufficient communication with key stakeholders, poorly designed exercises or assessment criteria, untrained assessors, and poorly administered sessions. At Phi, we follow professional standards for the design of assessment centres, such as the one provided by the British Psychological Society (BPS).

When is an assessment centre worth the investment?

The value of an assessment centre depends on the variability of performance in the role, the competitiveness of the selection process, the predictive validity of the assessment method, and the financial impact of the role [Source: Schmidt and Hunter 1998]. Assessment centres are most likely to deliver a strong return when they support high-impact decisions where selecting the right candidate can make a meaningful difference to organisational outcomes.

How do you prepare participants for a centre?

Participants should understand what the assessment centre involves and why it is being conducted. Clear communication helps participants prepare appropriately and supports transparency throughout the process.

A briefing pack should do more than provide logistical details. It should explain the purpose of the assessment centre, the types of exercises participants will complete, the competencies being assessed, and how participants can prepare. It should also outline how the results will be used, what decisions or recommendations may be informed by them, who will have access to the results, and how long the information will be retained.

In addition, participants should receive practical information such as dates, timings, locations, and instructions for requesting any reasonable adjustments or accommodations they may require. The briefing materials should be shared sufficiently in advance to allow participants to prepare adequately.

This is particularly important for internal candidates, who are being assessed by an organisation they already belong to. Providing clear information about the process, its purpose, and how the results will be used helps build trust in the assessment and encourages participant engagement.

Clear communication also supports fairness. Some participants may be familiar with assessment centres through previous experience, while others may be encountering the format for the first time. Providing consistent information to all participants helps ensure that everyone understands what to expect and how to prepare.

How Phi Management runs assessment and development centres

We have spent almost two decades designing and running centres for organisations across France, Lebanon and the Gulf, and we are accredited across the major psychometric instruments including Hogan, Saville, Lumina, Belbin and Everything DiSC. Our approach combines psychometrics with simulation exercises so that each competency is evidenced from multiple sources.

Centres are designed around your framework and your roles, not a catalogue. Where the output is developmental, we connect it directly to accelerator programmes, leadership academies or executive coaching so the insight turns into behaviour change. You can see examples of this in our case studies, and more about our approach in our methodology.

Frequently asked questions

How long does an assessment centre take? Most run for one to three days per cohort, usually with eight to twenty participants. Design and competency mapping usually takes two to four weeks beforehand, and feedback sessions follow within two weeks afterwards so the experience stays fresh for participants.

Can assessment centres be run virtually? Yes, and virtual delivery works well for in-tray exercises, case analyses, presentations and structured interviews. Group exercises are harder to observe remotely because you lose peripheral behaviour, so it is important to ensure that the group activity exercise can be reliably assessed virtually before centre execution.

Do participants receive their results? In a development centre, always, and the report belongs to the participant. In a selection centre, good practice is to offer every candidate a feedback conversation regardless of outcome. It costs little, protects your employer brand, and internal candidates who were unsuccessful are usually the ones who need it most.

Who should act as assessors? A mix of trained internal managers from at least one level above the target role, plus at least one external assessor, gives the best balance. Internal assessors understand the context and carry the outcome credibly inside the business. An external assessor interrupts shared assumptions and is not carrying a history with any participant. Assessor training is not optional, and a half-day briefing does not count as training.

What is the difference between a centre and psychometric testing? Psychometrics measure underlying traits and reasoning ability through questionnaires and tests. A centre observes behaviour in simulated situations. They answer different questions, which is why the strongest processes use both together rather than choosing between them.

The bottom line

An assessment and development centre replaces impression with evidence at exactly the moments where a wrong decision costs the most. The method is well established and the research behind it is strong, but the value comes from disciplined design, trained assessors and genuine follow-through. If you are weighing a senior appointment or building a succession shortlist, talk to an expert at Phi Management or explore our leadership assessment solutions.