This qualitative case-study research examined the influence of childhood and adolescent music performance experiences on self-efficacy and perceptions of success in adults. Eight 26- to 32-year-old, college-educated, adult professionals sharing membership in the same "a cappella" music performing group were observed, interviewed, and completed demographic surveys and self-efficacy instruments. Participants consisted of five females and three males, five of whom were white, one black, and one Asian/Pacific Islander. The research was designed to examine the potential impact of music performance experiences on individual's perceived self-efficacy and perceptions of success and how changes in these may generalize to other cognitive and affective domains. Analysis of participant interviews indicated that seven of eight regarded their music performance experiences as important contributors to their high efficacy expectations both in and out of music as well as their overall feelings of successfulness. Results of The General Self-Efficacy Scale confirmed this analysis in higher than average scores in seven of eight participants. Results of The Music Performance Self-Efficacy Scale reflected higher than average music self-efficacy expectations for all eight participants. Participants reported considerable, and in some cases, life-changing social benefits associated with their music performance experiences. Future research should be conducted to determine how participation in music performance can enhance social connectedness and to determine the conditions under which music performance experiences, including neuropsychological changes attending prolonged involvement in music performance, optimally enhance music performance achievement, self-efficacy, and perceptions of success, and how these may be generalized to other cognitive and affective domains. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]