Network-based approaches to improvement and specifically, peer challenges have become an integral part of quality assurance in adult social work in England. Whilst the national regulation change in 2011 placed greater weight on local accountability, very few studies have examined the contribution of peer challenges towards improving the quality of adult social work practice. Peer challenge is a process of engaging a wide range of people and experienced peers in relevant service areas to offer a review from the perspective of a critical friend. This article considers how a regional peer challenge process in the West Midlands of England contributed to improving social work practice and processes, which supported this contribution. Drawing on data from fifteen interviews and forty-four survey responses, findings suggest that peer challenges in the short term can have positive impacts including, an understanding of the internal practice conditions and external context, strengths and limitations of social work practice, and the perspectives of local stakeholders and external peers on opportunities to improve practice. The design, commitment to transparency and trust by all parties enable honest reflection and a shared learning experience. To understand long-term impacts, we suggest establishing formal follow-up processes together with developing key baseline indicators to track impacts.