We conceptually define and empirically investigate the accumulation of work experience—a concept that refers to the extent to which executives have amassed varied levels of roles and responsibilities (i.e., contributor, manager, lead strategist) in each of the key work activities that they have encountered over the course of their careers. In studying executives’ work experience accumulation, we consider key antecedents such as executives’ cognitive ability and personality traits, namely Extraversion and Openness to Experience, and examine the value of work experience accumulation on executives’ strategic thinking competency. Analyses of multisource data from 703 executives revealed 3 key findings: (a) accumulated work experience positively relates to executives’ strategic thinking competency after controlling for individual characteristics and other measures of work experience; (b) executives’ cognitive ability demonstrates the strongest and most positive relationship to executives’ strategic thinking competency; and (c) extraverted executives tend to achieve higher levels of work experience accumulation. Relative weight analyses also indicated that cognitive ability and accumulated work experience are the 2 most important predictors for executives’ strategic thinking competency among the other predictors. These findings are discussed in light of their practical implications.