The objective of the article is to identify the conditions that best explain organizational variance in policy evaluation regularity. Relying on the innovative Most Similar Different Outcome/Most Different Similar Outcome technique, we examine the explanatory ability of a range of organizational attributes applied to eighteen Flemish public sector organizations (Belgium). The conditions that relate to the source of evaluation demand, in its broadest sense, are of key importance. We refer to the role of the sector minister and other organizations in demanding evaluations, as well as to the media and parliamentary attention and the influence of EU evaluation clauses.