What a competency-based interview is and how it works
A competency-based interview (also called a behavioral interview or structured interview) assesses candidates on a defined set of competencies, skills, or behavioural indicators, usually derived from a job analysis of what the role requires. Each question is designed to probe one or more specific competencies, and the interviewer uses a structured scoring guide to evaluate each answer against defined criteria.
This format is used by most large UK employers (government, NHS, financial services, consulting, large corporates) and is the dominant format for graduate and management-level hiring. The defining characteristic is that every question asks for a specific past example: "Tell me about a time when..." or "Describe a situation where..." Generic or theoretical answers are not what is being asked for, and competency interviewers are trained to follow up with "Can you give me a specific example?" if a candidate answers theoretically.
How to identify and prepare your examples
Before a competency interview, research the competency framework used by the organisation. Many public sector employers (Civil Service, NHS, local government) publish their competency frameworks. For corporate employers, the job description often lists the competencies being assessed by name ("collaboration," "delivering results," "customer focus," "leading others"). Map each listed competency to one or two strong examples from your experience.
How to build a good example bank: List the ten to fifteen most significant pieces of work or experiences in your career. For each one, identify which competencies it could illustrate. You will find that some experiences cover multiple competencies (a project that required leadership, stakeholder management, and delivering results simultaneously). These versatile examples are your best assets: with different emphases, the same experience can answer several different questions.
For each example, apply the STAR structure: Situation (what was the context?), Task (what was your specific responsibility?), Action (what did you do, step by step?), Result (what was the outcome, and how did you measure it?). The Action section should be the longest part of every answer. The mistake most candidates make is spending too much time on Situation and too little on Action.
Civil Service Competency Framework and Success Profiles
The UK Civil Service uses the Success Profiles framework, which includes Behaviours (competency-based questions), Strengths (what energises you), Experience (your work history), Technical (role-specific knowledge), and Ability (aptitude testing). Behavioural questions in Civil Service interviews are assessed using the STAR structure against published behaviour descriptors at each level (from AA to SCS). Reading the behaviour descriptors for the grade and behaviours listed in the job specification is the most effective Civil Service interview preparation available: the descriptors tell you exactly what the assessors are looking for.