Standing sentinel in my kitchen is a tea mug with the legend: ‘We love policy that works’. A gift from the government's Evaluation Task Force, it serves to remind me why evaluation is important in providing information that can contribute to shaping and making policy decisions, and in their actualisation. It is also a daily reminder that evaluation still has some way to go before that potential is widely realised. This is the starting point for this book.

This is not to criticise what evaluation, in its many guises, does; it is instead a reflection on what it is currently not (widely) achieving. This is, of course, an unfair generalisation. Evaluations, and evaluators, can and do make a difference, not just in the domain of public policy but also elsewhere. Overall, however, the conversion of an evaluation process (and delivery) into a distinct, valued and maximised contribution to decisions would appear to be sub- optimal.

Evidencing any evaluation impact is itself challenging, especially when the dynamics of decision- making means it is impractical to isolate an acknowledged contribution from any one influencing source – evaluative evidence or otherwise. Nonetheless, the lack of contribution and profile of systematic, objectivised evidence is a widespread concern in the evaluation community and a commonly shared frustration in evaluator networks.

Paradoxically, more political institutions, public interest bodies and others are explicitly committing to using evidence in decision- making. Some go so far as to say they are, or are aiming to be, evidence- led in their policy and practice.