This article proposes a theoretical model for explaining the psychometric effects of faking on assessment procedures (e.g., biodata, interviews, assessment center, personality inventories, and self‐reported measures). The model hypothesizes that faking is a phenomenon of homogenization of scores, consisting of a double mechanism that increases the mean, on one hand, and decreases the standard deviation of distributions of scores, on the other. Subsequently, this affects the covariance, reliability, and validity of assessment procedures negatively. The model predicts that a mean ratio (faking ratio) greater than 1 and a coefficient of homogeneity u smaller than 1 characterizes faking. Meta‐analysis was used to test several predictions of the theoretical model in the case of the personality measures. A database of 46 independent studies was created. All the studies used the NEO‐PI‐R for assessing the Big Five and their facets. The general pattern of data fully supported the model predictions. Implications for personnel assessment and, particularly, for personality assessment are discussed.