Mental health problems are associated with significant losses in work productivity and, consequently, have significant ramifications for business entities and the general economy. Several instruments have been developed to measure productivity-related constructs such as absenteeism and presenteeism. The current study examines the utility of the Outcome Questionnaire-45 (OQ), a commonly used mental health questionnaire, in predicting work productivity. This relationship is explored as a preliminary step in assessing the degree to which changes in mental health brought about by psychotherapy will improve work productivity. Forty-nine participants were recruited from a call center in a small market research firm based in the Western United States. Work productivity was measured using four subscales of the Work Productivity and Activity Impairment (WPAI) questionnaire as well as an objective measure. The OQ and WPAI were administered on a weekly basis over the course of five weeks. Participant characteristic variables and work-time variables were also measured. A mixed models analysis of covariance (ANCOVA) with repeated measures showed that the Social Role (SR) Scale, a subscale of the OQ, was a significant predictor of Presenteeism, Overall Work Impairment, and Activity Impairment subscales. Latent growth modeling (LGM) was used to examine the relationship between the variables while accounting for individual trajectory differences. Although the results suggested that an unconditional model of Overall Work Impairment with SR as a time-varying covariate provided a good fit for the data, standardized regression weights between the variables were not significant. Implications of findings, limitations, and recommendations for future research are discussed.