Hom, Griffeth, and Sellaro's (1984) theoretical alternative to Mobley's (1977) turnover model was investigated in two studies. In Study 1, conceptual distinctions among model constructs and operationalizations of those constructs were validated. 206 nurses were surveyed, and constructs were assessed with multiple indicators. Although discriminating most constructs, structural equation modeling (SEM) identified a more parsimonious conceptualization in which a general construct underlies withdrawal cognitions. Other SEM analyses supported the indicators' construct validity and Hom et al.'s structural network. In Study 2, a longitudinal analogue of Hom et al.'s model was tested. A survey of 129 new nurses measured model constructs on three occasions. SEM disclosed that some causal effects in this model materialized contemporaneously, whereas others emerged after a lengthy time. Moreover, these causal effects systematically changed during newcomer assimilation. Implications for future research of turnover models are discussed.