As part of an embedded mixed-method study, qualitative research was conducted to understand how Engineering Is Elementary (EiE) professional development influenced the self-efficacy of K-5 elementary teachers required to teach engineering in a rural school in Southeastern, North Carolina. In fall 2016, proportional stratified sampling was used to select 14 teachers by grade level and specialty area who participated in EiE training. Teachers were interviewed to obtain in-depth information about their perceived self-efficacy. The interviews were transcribed and analyzed for content by person, by interview questions, and across all interviews using narrative data analysis methods. The data showed three themes: (a) teachers feel preparation programs lack STEM training, (b) integrating engineering is achievable in the K-5 classroom, and (c) professional support is an issue in improving this engineering initiative. The results demonstrated how elementary educators' self-efficacy evolved while engaging in professional development to prepare to teach engineering. Implications for educational practice and research are provided.