This study explored primarily the elementary teachers' motivations and expectations for engagement in a science professional development. Participants (N=20) were elementary teachers in two public schools from the United States and were enrolled in a yearlong science professional development; however, due to various factors teachers did not complete the professional development program. We investigated various motivational aspects related to teachers' professional experiences as well as their views about the program. Study results showed that teachers' motivations for this professional development program were strongly influenced by their self-efficacy beliefs about science teaching, their beliefs about what effective teaching means and the types of support provided to teachers by their schools to engage in such program. Additional study results showed that teachers from different grade levels perceived differently the effectiveness of their professional development program involvement because of the relevance (or lack of relevance) of the science content presented in the program relative to their grade level. Implications for classroom practice and future research are discussed in this study along with findings.