We examined the ways that faculty members developed as inclusive instructors as a result of participating in the Inclusive STEM Teaching Project (ISTP). The ISTP is a free, Massive Open Online Course designed to train STEM faculty members in inclusive teaching. Semi-structured interviews (n = 80) with course participants from multiple disciplines and institution types demonstrated increases in reflective capacity and awareness of inclusive teaching concepts and strategies, changes in mindsets and perspectives, validation of pre-existing beliefs, increases in self-efficacy, and the implementation of inclusive practices in and outside of the classroom. Results demonstrate a high degree of interconnectivity among empathy, self-efficacy, implementation, and ongoing self-awareness that point to an interactive and recursive understanding of inclusive teaching development. Results can be applied more generally in teaching and learning spaces and can be combined with similar attempts to embed inclusivity, diversity, and equity into programmatic and institutional ethos. Future research could build upon this work by increasing attention on the supports and barriers faculty members face as they attempt to implement inclusive practices.