Understanding factors contributing to the persistence and retention of women and underrepresented minorities within science, technology, engineering, and mathematics (STEM) is among the main issues of concern within STEM education. The available literature suggests that teacher self-disclosure, intrinsic motivation, and emotional and behavioral engagement play a significant positive role in the learning process across disciplines (e.g., Cayanus & Martin, 2016; Henry & Thorsen, 2019). Such factors may lead to improved academic achievements and retention in STEM disciplines (e.g., Simon et al., 2015). Additionally, a variety of studies examined the relationship between teacher self-disclosure, intrinsic motivation, and emotional and behavioral engagement within the field of humanities, but less within the fields of STEM. Using a self-reported survey adapted from available instruments on teacher self-disclosure, intrinsic motivation, and emotional and behavioral engagement, data was collected from 208 participants enrolled in a two-year Freshman Research Immersion program at one university. Using Structural Equation Model (SEM), this study examined the relationship between teacher self-disclosure, intrinsic motivation, and emotional and behavioral engagement of undergraduate students enrolled in a STEM research program, a research program provided for students interested in STEM fields during their undergraduate years. Specifically, the analysis examined the association between the four latent variables. First, the obtained results showed a direct relationship between teacher self-disclosure instances perceived as relevant to the course content and factors of STEM students' feelings of motivation (e.g., enjoyment) and their engagement within the learning context (e.g., interest). Second, findings demonstrated that students enrolled in STEM research classes associated feelings of interest and decreased levels of anxiety and frustration with feeling a sense of enjoyment during their research courses. Finally, results showed that when STEM research program students enjoyed the course, they felt more competent and attentive during STEM research classes. The study's significance lies in practical recommendations associated with strategic use of instances of teacher self-disclosure while teaching STEM classes and ways to support STEM students' levels of intrinsic motivation and classroom engagement by showing the relationship between the two within STEM. [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.]