Program-theory approaches to evaluation have gained acceptability over the past 25 years as a means for examining conditions for implementation that are associated with better outcomes and developing detailed program theory. They have also gained confusion, as witnessed in the review of recent studies in this article. (Author/SLD)

In the last 10 years, there has been increased use of case study methodology, with accompanying refinement and improvement of the methods. Case studies have become legitimate research methods in evaluation, but it is too soon to say whether improvements in methodology are really resulting in improvements in the case studies conducted. (SLD)

It is argued that, although thousands of evaluations have been conducted of social interventions, little has been done to cumulate those results to guide intervention architects. Building social intervention theory and meta analyses are suggested as ways to unify this knowledge and make it useful. (SLD)

The seven articles of this special issue focus on theory and research related to survey methods and whether evaluators need information that is absent from the larger survey literature. These articles reflect the view that the considerations relating to good survey research apply also to using surveys in evaluation. (SLD)