The perfectionism field has advanced considerably over the past 25 years, but researchers typically focus on substantive findings, and there has been comparatively little systematic emphasis on measurement issues. This special issue introduces new perfectionism measures and examines several important measurement topics. This special issue advances the theme that how constructs are conceptualized and measured has a direct impact on the findings that emerge in empirical research. We provide an overview of specific topics addressed in this special issue, including the importance of distinguishing between perfectionism versus conscientiousness and the role of assessment in documenting the heterogeneity that exists among people who all describe themselves as perfectionists. It is evident from the papers in this special issue that the complexities inherent in the perfectionism construct require an equally complex and sophisticated measurement approach. Further advances in the perfectionism field depend largely on implementing a programmatic approach to measurement and assessment.