This article describes key features of a hybrid professional development (PD) program that was designed to prepare elementary classroom teachers to mentor preservice teachers for effective science instruction. Five classroom teachers who were new to our mentor training participated in the study to document the impacts of the PD sequence. The PD combined an in-person immersion into the components of effective science instruction with online modules centered on learner-supportive mentoring practices. The authors detail key aspects of this hybrid program and discuss its impacts on the cooperating teachers' ability to facilitate effective mentoring conversations with preservice teachers. Findings indicated that mentors who engaged in the hybrid face-to-face and online PD more effectively coached their mentees and displayed specific shifts in their approach to mentor conversations. Participants showed statistically significant increases in their ability to use coaching as a default mentoring stance, to focus on evidence of students' science learning, and to draw on a consistent framework for effective science instruction for their conversations. These findings support a hybrid model of PD for mentoring and create potential for exploring a fully online sequence to promote effective mentoring in future work.