The interview is the most frequently employed tool for selecting personnel. The professional and scientific literature on the subject suggests that interviews can be divided in two broad categories: the structured and non-structured format, the first one being considered more valid, more reliable and less biased. Two types of structured interviews have been recognized, the situational and the behavioural interviews.

Popularized by Gary Latham and his colleagues around 1980, situational questions are written to situate candidates in a hypothetical, but job-relevant situation, so that they can describe their future behaviour, or their behavioural intentions. This type of question reveals two things from successful candidates: a) that they know how to act in that particular hypothetical situation, and b) that they have the knowledge required to deal with that situation.

Situational questions make it possible to predict future behaviour because they reveal the objectives governing the candidate's actions in this kind of situation. According to Locke's motivation theory, behavioural intentions are the precursors of action. It is important to give candidates several situations to deal with, in order to appreciate the consistency of their behavioural intentions.

Behavioural questions first appeared in the 1960s, but were popularized by Tom Janz (1982), who called the technique behavioural description interviewing. Behavioural questions require the candidate to describe what he or she did in a past situation more or less similar to a situation that might arise in the job.

Past behaviours predict future performance because they reveal the choices a person has made and therefore describe his or her usual patterns of behaviour. To evaluate the consistency of a person's performance, it is important to ask for more than one example of behaviour or situation per competency.

Also, in order for the interviewer to really understand a person's past behavior, the example must present the following three aspects:
a) The situation that led to the candidate's actions, or in which the actions took place
b) The candidate's specific actions
c) The results or consequences that ensued from the actions

To be complete, each description of past behaviour must include these three components. As a result, the interviewer must usually adopt a two-stage approach: formulation of the main question, and then if necessary, prompting questions.