Efforts to test hypotheses derived from social cognitive theory require sound measures of the theory's constructs. Because the theory is concerned with domain-specific aspects of human functioning, it raises special measurement challenges. For example, unlike traits, which can be indexed with general, all-purpose measures, social cognitive research calls for measures that are tailored to the specific domain and dependent variables of interest. To facilitate social cognitive research on career development, a guide is provided for conceptualizing and assessing the core constructs of social cognitive career theory: self-efficacy, outcome expectations, interests, goals, and contextual supports and barriers. The basic constructs and their common variants are defined and distinguished, unique measurement concerns are considered, and examples and suggestions are offered for measurement design and adaptation.