Background: An effective preceptor is a vital component of a strong learning experience for learners. Many clinical preceptors provide on-site supervision and clinical teaching but lack the skills necessary to be effective teachers. Few studies have examined the factors related to teaching competence among clinical nurse preceptors.
　　Purpose: This article is a report of a study that examined (a) the differences in teaching competence by preceptor background, (b) the influence of locus of control on self-evaluated teaching competence, (c) the association between self-directed learning and self-evaluated teaching competence, and (d) the predictors of self-evaluated teaching competence among clinical nurse preceptors.
　　Methods: This descriptive and correlational study used a crosssectional survey of a convenience sample of 243 clinical nurse preceptors from a medical center in northern Taiwan. Of these, 242 completed questionnaires for an effective response rate of 99.6%. The self-evaluated Teaching Competencies Scale, InternalYExternal Scale, and Self-Directed Learning Instrument were used to assess teaching competencies and related factors among clinical nurse preceptors. Descriptive statistics, one-way ANOVA, MannYWhitney test, and multivariate linear regression were used to analyze data.
　　Results: Clinical nurse preceptors averaged 4.03 in teaching competence, indicating a moderately above average score. Higher teaching competence was associated with older age, being married, 910-year work experience, not assigned by unit manager, and good internal locus of control. Self-directed learning significantly correlated with teaching competence (r = .62). Internal locus of control and self-directed learning were significant independent predictors of teaching competence after adjusting for age, marital status, total years as a clinical nurse preceptor, and willingness to be a clinical nurse preceptor. Together, these accounted for 33.6% of teaching competence variance.
　　Conclusions: Nurse managers should recognize all factors and characteristics of clinical nurse preceptors that influence teaching competence to help achieve optimal learning outcomes for nursing staff and students.