As described in the introductory chapter, this book is concerned with the ways that actors in particular policy formulation venues gather and apply knowledge derived from using particular policy formulation tools. This chapter examines the venue of policy appraisal, which has received widespread attention from both policy formulation researchers and practitioners in the past two decades (Turnpenny et al. 2009; Adelle et al. 2012). As a formalized venue in which analysis is undertaken when formulating policy, it corresponds to the ‘Internal-Official’ type as defined in Chapter 1. Indeed, the use of policy appraisal is often required by law: by 2008, all 31 OECD countries had either adopted, or were in the process of adopting, a formal system of policy appraisal (OECD 2009). Policy appraisal systems may in turn harness a wide range of policy formulation tools to carry out the analysis (Carley 1980; De Ridder et al. 2007; Nilsson et al. 2008). All these elements mean that the study of policy appraisal can yield revealing insights into policy formulation as a whole, since it covers, often mandatorily, the key ‘tasks’ of policy formulation noted in Chapter 1, namely: characterization of the current situation; problem conceptualization; identification of policy options; assessment of potential policy options and recommending and/or proposing a specific policy design.