This special issue of Sociological Methods & Research contributes to recent trends in studies that exploit the availability of multiple measures in sample surveys in order to detect the level and patterning to measurement errors. Articles in this volume focus on topics in one of (or some combination of) the three areas: (1) those that develop and test theoretical hypotheses regarding the behavior of measurement errors under specific conditions of measurement, (2) those that focus on the methodological problems encountered in the design of data collection permitting the estimation of measurement models, and (3) those that focus on the evaluation of existing models for detecting and quantifying the nature of measurement errors. The designs included in these investigations include those that incorporate follow-up probes, record-check studies, multitrait-multimethod designs, longitudinal designs, and latent class models for assessing measurement errors for categorical variables.