Although many studies have examined the sources that enhance learners' self-efficacy, few have considered how preconceptions about failure might influence self-efficacy development, particularly in areas where failure is common. This study investigates how learners' preconceptions about failure are related to self-efficacy in the domain of robotics. The relationship between failure mindset and robotics self-efficacy was investigated during a weeklong STEM camp for children in Grades 4-7 (N = 237). Regression results indicated that failure mindset was a significant predictor of robotics self-efficacy, controlling for gender, school level, and race. Although elementary learners generally had higher robotics self-efficacy, the relationship between failure mindset and robotics self-efficacy was stronger for middle school learners. Implications for future research and classroom applications are discussed.