Little is known about the impact of science fair participation on student science inquiry learning. Furthermore, there is only a small research base relating to science fair participation and student attitudes toward science, technology, engineering, and mathematics (STEM) careers and coursework. In this study, 41 seventh-grade science fair contestants from three schools participated in focus group sessions to qualitatively assess their interest in STEM careers and coursework and their understanding of science inquiry. Science fair participation increased student understanding of science inquiry, and positively influenced the attitudes of the majority of students in the study toward STEM courses and careers. The strengths of the science fair programs were a focus on science inquiry as well as student choice in choosing and carrying out projects. However, for a subgroup of students, the stress level they experienced as they worked on their projects resulted in negative attitudes toward STEM fields. The length and complexity of the science fair process was of concern for many students, but especially so for this sub-group. It is possible that an undertaking of the length and complexity of a typical science fair project is not appropriate for all students in this age group. Alternatives for students include carrying out several shorter projects, rather than one large project, or working with partners or small groups. These strategies could serve the larger goals of increasing student science inquiry understanding and increasing positive student attitudes toward STEM fields in a more age-appropriate manner.