Social Work qualifying programmes teach students the necessary knowledge, skills, and values during a series of taught modules. Formal opportunities to integrate knowledge into practice are provided through practice placements in social work agencies. Each practice placement enables agency and/or academic staff to gate-keep entry into the profession, through assessing student competence against agreed practice learning requirements, readiness to practice, and adherence to professional social work standards. This research study seeks to expand our understanding of the incidence of and reasons why students failed their practice placement whilst studying social work on the island of Ireland. On receipt of ethical approval, Practice Teacher reports and minutes of Practice Assessment Panels were used for data collection. Sixtythree students (19 male, 44 female; mean age 34 years) failed placement 2015-2019, with the majority (58.7%) failing first placement. Reasons for failing were categorised into knowledge, skills, values and personal reasons. The most common reasons for failing were a poor understanding of the professional social work role, poor time management, poor written work, the inability to follow direction, limited application of knowledge to practice, and poor professional conduct. Results suggest most students disclosed mitigating circumstances, which affected engagement and competence.