This article utilizes the findings of a recently completed, eight-country research project to visit some key issues in the theory and practice of gender mainstreaming. The research results indicate that gender mainstreaming is a diverse entity when looked at from a cross-national perspective but rather hollow when considered within the national setting. To the extent that there is a “common core” to gender mainstreaming in action across countries, it lies in the tendency to apply the approach in a technocratic way and to be nonsystemic in compass. The argument is advanced that this is at least in part attributable to particularities in the development of mainstreaming. The article suggests that gender mainstreaming is underdeveloped as a concept and identifies a need to elaborate further on some fundaments. In particular, the conceptualization of mainstreaming needs to be rethought with special attention devoted to the understanding of the problematic of gender inequality that underlies it and the articulation of the relationship between gender mainstreaming and societal change.