Theory in evaluation: Reducing confusion and encouraging debate

One of the goals of the journal Evaluation was to advance theoretical and methodological understandings of evaluation. Twenty years later theory as understood in the field of evaluation is fragmented, a problem widely recognized in the evaluation community. The goal of this article is to make a modest contribution to clarifying this situation. We first present two typologies of evaluation theory and invite readers to join us in a discussion of the pros and cons of these typologies. We then present an impressionistic picture, mainly qualitative, of how theory' has featured in past issues of this journal. Many articles with a theoretical orientation have been published in Evaluation providing a rich though somewhat diffuse picture in which many of the types identified in our typologies are represented. Finally several suggestions are put forward to further strengthen the development of theoretical work in the evaluation profession. These are theory knitting', theory layering' and theory-driven evaluation science'.