Purpose: The primary purpose of the study was to evaluate the effect of an educational intervention including the use of a clinical reference tool on the clinician's knowledge and self-efficacy scores in peristomal management. A secondary purpose compared the participant's knowledge and self-efficacy based on the education delivery method of online education as compared to in-person. Design: This education project was a two-group, pre/posttest, descriptive design used to evaluate changes in knowledge and self-efficacy in ostomy management post education intervention. Subjects and Setting: The study groups included physical therapist, nurse, nurse practitioner, physician assistant, and physician practicing in a variety of healthcare areas in the United States. Online participants (n=64) were scattered geographically across thirteen different states, and the in-person groups (n=89) were located in New Jersey, South Carolina, and Hawaii. Methods: The groups received education (PowerPoint presentations) and a quick reference clinical tool regarding stomal and peristomal presentations and complications. The participants completed pre/post education surveys evaluating knowledge and self-efficacy. Results: For the total sample, there was a statistically significant increase in knowledge scores from pre-intervention to post-intervention, t(106) = -16.03, p < 0.001 and a statistically significant increase in self-efficacy scores, t(115) = -6.49, p < 0.001. The knowledge rate of growth was greater in the in-person learning however the self-efficacy scores improved at a higher rate in the online group. Conclusions: This doctoral project focused on a teaching methodology and its effect on the learner regarding peristomal assessment and treatment. The results have carry-over implications on education techniques and methods of testing knowledge. Online and in-person instruction mutually show improvement in knowledge and self-efficacy. The level of improvement may individually differ according to the teaching methodology and testing approach. Thus, a varied education and testing style is recommended for best knowledge acquisition and implementation into practice. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]