Registered apprenticeship (RA) programs have emerged in recent years in response to the nation's critical workforce needs. Since 2015, there has been a resurgence of federal and state investments to modernize and diversify the RA system to attract new entrants and new high-demand industries. This study uses human capital theory (HCT) as a lens for exploring the lived experiences and training investment decisions of seven Black women who participated in science, technology, engineering, and math (STEM) RAs. The study participants experienced a combination of on-the-job learning and classroom instruction in a range of STEM RA programs. These programs ranged from being highly structured and competency based, with degree-level credentials, to being less structured; all provided industry-recognized credentials from a community college, university, or training program. The study yielded five primary findings: apprentices needed certain characteristics to enter, participate, and succeed in STEM RAs; apprentices capitalized on rotational opportunities and mentors to adapt to the demands of STEM RAs; the dual structure of STEM RAs helped apprentices feel prepared for success in the workplace; STEM RAs provided financial and nonfinancial benefits, including improvements to interpersonal skills and professional networks; and feelings of recognition and inclusion resulted in a sense of belonging in participants. This study confirmed, in part, that Black women's completion of STEM RA programs should result in increased competencies, wages, employment opportunities, and productivity. In addition, this research confirmed the limitations of HCT by revealing the emotional turmoil that comes from being underrepresented. [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/en-US/products/dissertations/individuals.shtml.]