Project-based learning (PBL) has a positive impact on student motivation, students' perceived learning, and performance. However, many teachers are reluctant to adopt PBL. This mixed-methods study examined in-service teachers' learning experiences of planning and implementing PBL situated in a graduate level PBL course and sought insight into the challenges and ways to overcome the challenges in implementing PBL in practice. Results indicate that teachers' confidence about their ability to plan and implement a PBL project improved upon completion of the course. Nevertheless, teachers cited various obstacles, such as a lack of mentoring, planning time and implementation experiences, which had prevented them from complete implementation of PBL in teaching. Possible ways to overcome the challenges in adopting PBL include school support, opportunities for experience and practice with PBL, and peer collaboration. The study also showed that a semester-long course focused on designing and developing a PBL project of teachers' choice was effective in helping increase their confidence and experience in potential implementation of PBL in classroom practice. This study contributes to the implementation of PBL in classrooms and teacher education as well as teacher professional development on the PBL approach.