There is growing interest in the development of evidence supporting therapeutic interventions in social work. Few examples, however, exist, of the use of validated instrumentation in measuring the impact of services upon children and families. We report here on the use of a suite of validated instruments to measure the impact of services on children and their parents in receipt of services provided by an Irish Non-Governmental Organisation (NGO) across their seven family centres. The NGO engaged a team of university-based researchers who provided training in the use of validated instruments, monitored implementation of their use and analysed the resulting data. Over a two-year period, 968 families were surveyed at Time 1 (entering the service), with 452 completing surveys at Time 2 (leaving the service). The results indicate a decrease in children’s emotional and social problems, with those with highest scores at Time 1 making most progress by Time 2. Similarly, it was evident that interventions had a positive impact upon parental mental health and, with regard to child–parent relationships, both children and their parents reported positive changes. Such findings lay emphasis on the importance of measuring the impact of services on individual psychological functioning and interfamilial relationships.