Although Objective Personality Tests (OPTs) have a long history in psychology and the field of psychological assessment, their validity, and reliability have not yet been sufficiently studied. In this study, we examined the convergent and discriminant validity of objective (personality) tests, Implicit Association Tests (IATs), and self-report measures for the assessment of conscientiousness and intelligence. Moreover, the convergent and discriminant validity of these measures was assessed on the trait (stable) and occasion specific (momentary) level by using the multimethod latent state-trait (MM-LST) model proposed by Courvoisier, Nussbeck, Eid, and Cole (2008) which allows for the decomposition of different sources of variance. Data from 367 students assessed on three different measurement occasions was incorporated. Results indicate generally low convergence of OPTs with data gained by other approaches. Additional analyses revealed that the OPTs used assess stable rather than momentary components of the constructs. Reliabilities of different tests ranged from.54 to.95. Furthermore, a substantial amount of trait method specificity revealed that different methods assess trait components that are not shared between OPTs and other measures. Data on the criterion validity of the objective conscientiousness test revealed that it is related to the punctuality of test takers in the laboratory.