This collection of essays, published to mark the 20th anniversary of Realistic Evaluation, celebrates the work of Professor Nick Tilley and his significant influence on the fields of policing, crime reduction and evaluation. With contributions from colleagues, co-authors and former students, many of whom are leading scholars in their own right, the thirteen essays which make up this volume contain both personal reflections and analysis of the prominent topics in Professor Tilley¿s forty years of scholarship.