Objective: This study examines the psychometrics of the 15-item version of the Five-Factor Mindfulness Questionnaire (FFMQ-15). Participants: An ethnically diverse sample of 538 college students participated in this study. Methods: The factor structure was evaluated through confirmatory factor analyses fitting 64 alternative models with and without method factors. Model fit as well as valid interpretations of the model parameters were considered in selecting the final model. Utilizing the final selected model, the relationship between mindfulness and the mindfulness facets with two related constructs, psychological inflexibility and emotional distress tolerance was examined. Results: The five-facet second-order model with a single-method factor best fitted to the data and provided sound, interpretable estimates. After accounting for the single-method effect, overall mindfulness was positively correlated with emotional distress tolerance and negatively correlated with psychological inflexibility. Conclusions: The FFMQ-15 was a valid measure of mindfulness among university students when accounting for the method factor.