Understanding how the disposition of a student interacts with or influences a behavior plays a central role in cognitive theories. Middle school years have been accounted for as being difficult, awkward, and sometimes downright stressful. The overall purpose of this action research was to examine the impact of a growth mindset innovation using a digital portfolio on the self-efficacy of middle school students in a leadership course. The research questions were: (1) How can a growth mindset intervention using a digital portfolio support self-efficacy improvement in middle school students taking a leadership course? (2) What are students' perceptions on their self-efficacy in giving a speech before and after implementing a growth mindset intervention? The participants consisted of (n = 23) middle school students in a related arts leadership semester-long course. This was a mixed methods study, collecting pretest and posttest survey responses and student interviews, journal responses, and digital portfolio activities. Two surveys were used to measure growth mindset and self-efficacy in public speaking. Quantitative data analysis showed significant growth from pre- to post-survey measuring student growth mindset. Students showed significant growth as well from pre- to post-survey results when measuring self-efficacy. Qualitative data were examined for belief in a growth mindset and ability to accomplish a task in a leadership course. Qualitative data analysis revealed students perceived the growth mindset innovation impacted self-efficacy in public speaking as well as other areas. Specifically, four themes were identified: (a) The innovation gave students a Growth mindset, (b) Growth Mindset gave strategies to students to support self-efficacy in multiple school and classroom areas, (c) correct methods with careless errors, and (d) Digital portfolios were designed to represent student knowledge, but students were impacted little by them. Implications for practice and future research are discussed, and limitations are identified. [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.]