There is an increasing awareness of out-of-school program value in enhancing student interest and understanding of science, technology, engineering, and mathematics (STEM). This study examined the impact of an out-of-school STEM education program on student attitudes toward STEM disciplines and STEM careers. A STEM education program implemented at a public research university was designed to integrate STEM disciplines with hands-on problem-based activities. Design features included authentic learning contexts, engineering design processes, and content integration. Data sources included an attitude survey and interviews conducted with forty sixth grade middle school student participants. The analysis revealed significant differences between pre and posttests on student attitudes toward personal and social implications of STEM, science and engineering learning, and their relationship to STEM. Findings showed that the program contributed to students' developing interest in STEM fields, and helped them make connections between schoolwork and daily lives. Recommendations for future research on out-of-school STEM education programs were discussed.