The purpose of the current study was to determine the impacts of a multiple-day engineering-focused professional development program on elementary teachers' perceptions of the work of engineers and their use of mathematics and science. Data were collected in the form of drawings of engineers prior to and immediately after the professional development program as well as an open-ended exit survey at the end of the program. Participants' drawings were scored in the following areas: use of mathematics, use of science, and work of an engineer. Wilcoxon signed-rank tests revealed that the only significant change between measures was in "work of an engineer," with participants' drawings representing more expanded conceptions after completing the professional development program. An analysis of exit survey responses indicated that participants still had a limited understanding of the complex relationships among engineering, science, and mathematics.