Abstract: The past two decades have seen an increasing interest in studying non-cognitive skills across disciplines. Despite the shared popularity, non-cognitive skills have been assessed variously across disciplines with different assumptions and target populations. Synthesizing across the commonalities, differences, and limitations in these various approaches will have important implications for the development and interpretation of non-cognitive assessments. In this project, we review the ways in which non-cognitive skills have been conceptualized and measured across psychology and education, and use self-control as an example to address the challenges to various types of assessments that are commonly seen in these disciplines. We will draw implications from a cross-disciplinary perspective on the validity and reliability of the non-cognitive assessments.