Professional Learning Communities (PLCs) are frequently being used as a vehicle to transform science education. This study explored elementary teachers' perceptions about the impact of participating in a science PLC on their own professional development. With the use of The Science Professional Learning Communities Survey and a semi-structured interview protocol, elementary teachers' perceptions of the goals of science PLCs, the constraints and benefits of participation in PLCs, and reported differences in the impact of PLC participation on novice and experienced teachers were examined. Sixty-five elementary teachers who participated in a science PLC were surveyed about their experiences, and a subsample of 16 teachers was interviewed. Results showed that most of the teachers reported their science PLC emphasized sharing ideas with other teachers as well as working to improve students' science standardized test scores. Teachers noted that the PLCs had impacted their science assessment practices as well as their lesson planning. However, a majority of the participants reported a differential impact of PLCs depending on a teacher's level of experience. PLCs were reported as being more beneficial to new teachers than experienced teachers. The interview results demonstrated that there were often competing goals and in some cases a loss of autonomy in planning science lessons. A significant concern was the impact of problematic interpersonal relationships and communication styles on the group functioning. The role of the PLC in addressing issues related to obtaining science resources and enhancing science content knowledge for elementary science teachers is discussed.