In a national and international context where there is a concern about the effectiveness of social care services for children and families to address chronic, enduring social problems and where there are finite resources available, the concept of social innovation in social work policy and practice to address need in new ways is receiving increased attention. While an attractive term, social innovation in child and family services is not without its challenges in terms of conceptualisation, operationalisation, implementation and evidencing impact. This article reports on the development and evaluation of the Early Intervention Support Service (EISS), a newly designed family support service in Northern Ireland set up as part of a government supported innovation and transformation programme that aims to deliver a voluntary, targeted, flexible and time limited service to families experiencing emergent problems. Using the EISS as a case study, the challenges, benefits in terms of addressing policy imperatives and future direction of social innovation in social work practice are reflected upon.