The purpose of this study was to add to the knowledge on the value of professional communities of practice as a performance improvement intervention. Value was defined as the awareness of the benefits and outcomes, provided as improvement in a tangible or intangible way, that positively impact organizations and/or individuals and their personal and professional environment. The problem with the research on the topic of the perceived value of participating in a professional community of practice was the accessibility of information. Previous studies yielded results that professional communities of practice provide value to an organizational environment. However, there was limited information on how individual community members described value in a tangible way. This performance improvement research study answered the question, how do members of a professional community of practice describe their perceived value from participating? This single-case, explanatory, qualitative case study provided rich descriptions of members' experiences of their (a) expectations when joining, (b) benefits realized from participating, (c) outcomes received due to participation, and (d) contributors to benefits and outcomes of perceived value from participating in a professional community of practice. The population was members of Toastmasters International, a learning professional community of practice. The sample groups were obtained from 2 sources: prerecorded Toastmasters International member testimonials published on www.toastmasters.org, and purposeful sampling of select tenured Toastmasters members who would be able to answer the research questions due to their experiences in the Toastmasters program. The data analysis included an innovative use of Thomas Gilbert's behavior engineering model. Whereas the model is normally used to find deficiencies that are hindering performance, for this case study, it was used to find the success factors that contributed to performance improvement. The answer to the research question could be summarized into two categories of findings. Research findings were that (a) members were able to evaluate their own participation as it pertained to tangible, quantifiable improvements in their performance (evidenced by 41% of the 49 participants' ability to articulate outcomes) and (b) the motivators of participation that resulted in value and personal improvement as defined by the individuals were nonquantifiable elements such as recognition and external opportunities, and benefits beyond their initial expectations. This research could be useful for other formal and informal communities of practice to evaluate value in their organizations. [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.]