This article examines practitioner perspectives on agency social work in Local Authority Children's Services Departments in England. There have been ongoing concerns about the use of agency workers, relating to cost, quality and impact on services, despite a recognition that temporary staff may be needed for a range of reasons. However, recent labour shortages and the escalating costs of agency staffing are fuelling calls for some form of regulation of agency workers. The article reviews literature on agency workers from the UK and elsewhere. It presents demographic survey data about agency workers drawn from a five-year longitudinal study on the recruitment and retention of child and family social workers and reports qualitative data from forty semi-structured interviews with social workers in Year 4 () of the project about their experience of agency social work and agency social workers. The findings indicate several reasons for choosing agency work, pay being the most significant but by no means the only one. The advantages and disadvantages of agency work for workers, employers and service users are considered, and suggestions are offered about further research to assist in understanding how employers can identify and address recruitment and retention factors to reduce dependence on agency staff. Local Authority Children's Services Departments in England often have to employ temporary agency social workers to fill gaps in their staffing. This is expensive and sometimes these workers do not stay in their jobs for long. For this article, we used information from a research study on the recruitment and retention of social workers which has been running for five years. This included surveys with information about the characteristics of agency workers, and interviews with forty social workers about the advantages and disadvantages of agency social work for people who use services, for workers and for employers. We found that although agency workers are sometimes needed, most social workers think that employers need to do more to encourage permanent staff to stay with them so that the numbers of agency workers can be reduced.