An extensive network of empirical relations has been identified in research on the psychological construct of self-monitoring. Nevertheless, in recent years some concerns have been expressed about the instrument used for the assessment of self-monitoring propensities, the Self-Monitoring Scale. Both the extent to which the measure taps an interpretable and meaningful causal variable and the extent to which the self-monitoring construct provides an appropriate theoretical understanding of this causal variable have been questioned. An examination of reanalyses of studies of self-monitoring, analyses of the internal structure of the Self-Monitoring Scale, and further relevant data suggest that the measure does tap a meaningful and interpretable causal variable with pervasive influences on social behavior, a variable reflected as a general self-monitoring factor. We discuss the evaluation and furthering of the interpretation of this latent causal variable, offer criteria for evaluating alternative measures of self-monitoring, and present a new, 18-item Self-Monitoring Scale.