The present study explores the validity of the Five Factor Dependency Inventory (FFDI), a measure of dependent personality traits from the perspective of the five factor model, examined across three separate samples and two studies. The first study examined the FFDI with respect to the traits assigned to assess dependent personality disorder (DPD) by the DSM-5 work group, two measures of DSM-IV-TR DPD and three measures of dependent traits, sampling 184 Mechanical Turk participants and 83 students (the latter oversampled for DPD features). Based on responses from an additional 137 students, the second study investigated the role of maladaptive agreeableness in dependency by examining the FFDI in relation to the interpersonal circumplex using three alternative measures. Discriminant validity was provided with respect to DSM-5 traits and the interpersonal circumplex. Incremental validity was provided with respect to the ability of the FFDI to account for variance within DPD measures beyond the variance explained by DSM-5 traits. Implications for the assessment of dependency and the proposed DSM-5 dimensional trait model are discussed.