The current study explored how a professional development program for differentiated instruction in science education supported change in preservice teachers, following the Interconnected Model of Professional Growth by Clarke and Hollingsworth. Among eight preservice teachers, a self-report questionnaire (pre and post) and reflective logbooks were used to identify changes in the four domains of the Interconnected Model of Professional Growth. Three out of the eight preservice teachers were additionally analyzed as embedded units using semi-structured interviews and classroom observations. The professional development program consisted of seven 2-h meetings, which included theory about differentiated instruction and science education, relevant pedagogical content knowledge, and both individual and group reflection. Two science lessons, with a focus on supporting high-achieving students and students with reading difficulties, were implemented by the preservice teachers in their internship schools and evaluated during the professional development program. For the embedded units of analysis, the preservice teachers implemented an additional follow-up lesson after completion of the professional development program. Overall, results showed that preservice teachers reported increased practice of differentiated instruction in science education, higher self-efficacy, and positive experiences with the professional development program. The use of the Interconnected Model of Professional Growth helped to illustrate aspects of the professional development program that may have contributed to change, while also nuancing the self-reported progress. The domain of consequence—specifically the ability of noticing—seems to be an important catalyst for teacher change. Taken together, these findings provide detailed insights into how teachers can be better prepared in meeting the needs of all students in science education.