This chapter illustrates the application of an agencywide approach to enable practitioners to use effectiveness research. The evaluation project was commissioned by the agency and began in response to the internal and external pressures on probation services to be more accountable to society and to demonstrate the effectiveness of their work. Single-case evaluation procedures included the use of recording systems to identify objectives, the intervention programmes and the means of monitoring client progress. The practitioners were encouraged to use published measures of high reliability and also to create their own measures appropriate to the needs of their clients. The chapter discusses four case examples from evaluation project—the first where considerable progress was achieved in most of the objectives, the second where progress was made in more than one objective, the third where progress was achieved in at least one objective, and the fourth where the situation for the client deteriorated during the period of supervision.