Social workers and probation officers are frequently called upon to make judgements about the likelihood of re-offending. However, whilst the use of risk assessment instruments is now commonplace, the cognitive processes through which these judgements are made are rarely explicit.

This study used the repertory grid method to elicit the constructs of judgements about re-offending of 15 experienced probation officers. Primary factors in their judgements were related to: (1) responsibility and risk taking behaviour; (2) criminal history; (3) self-awareness; and (4) stability. Personality characteristics, substance misuse and family dysfunction were also important. The findings are discussed in relation to two theoretical frameworks for understanding decision making: heuristics and biases and image theory, which focuses on values.

It is suggested that the design and implementation of assessment tools should be undertaken in the light of the constructs used in making professional judgements which inform the relevant decision making.