Background: Breastfeeding competencies are not standardized in healthcare education for any of the health professions. A few continuing education/professional development programs have been implemented, but research regarding the efficacy of these programs is scarce. Research aim: After a 45-hour lactation course, (a) Does breastfeeding knowledge increase? (b) Do beliefs and attitudes about infant feeding improve? (c) Does perceived behavioral control over performance of evidence-based lactation support practices increase? and (d) Do intentions to carry out evidence-based lactation support practices increase? Methods: A nonexperimental pretest–posttest self-report survey design was conducted with a nonprobability sample of participants ( N = 71) in a lactation course. Theory of Planned Behavior variables were measured and a before–after course analysis was completed. Results: Significantly higher scores were found on the posttests for knowledge, beliefs about breastfeeding scale, and the perceived behavioral control scale. Participants’ self-efficacy increased after the course; their beliefs about social norms and their ability to effect change in their workplaces did not change significantly. Participants’ intention to perform actions that are consistent with the evidence-based breastfeeding supportive behaviors increased significantly. Positive beliefs about formula feeding significantly increased; this was unexpected. Conclusion: The Theory of Planned Behavior provided a useful approach for examining more meaningful learning outcomes than the traditional knowledge and/or satisfaction outcomes. This study was the first to suggest that more meaningful learning outcomes are needed to evaluate lactation programs. However, it is not enough to educate healthcare providers in evidence-based practice; the places they practice must have the infrastructure to support evidence-based practice.