We are extremely grateful to a large number of scholars who provided feedback that greatly strengthened this work. The authors of the theories this work was based on for their generosity in meeting with us and discussing ideas: Carol Dweck, Aneeta Rattan, and Andrei Cimpian. Experts who provided feedback on the draft items: Connie Barroso Garcia, Jeni Burnette, Michael Barger, Andrei Cimpian, Lisa Corwin, Caitlyn Jones, Sandhya Krishnan, Katie Kroeper, Paul O’Keefe, Katie Muenks, Heidi Williams, Mary Murphy, and Aneeta Rattan. Advisory board members who provided extensive feedback throughout the project: Debbi Bandalos, Bill Boone, Allan Cohen, and Mary Murphy. Finally, thank you to two anonymous reviewers and monitoring editor Ross Nehm who carefully reviewed earlier versions of this manuscript and provided extensive, helpful feedback. The work was supported in part by the National Science Foundation’s Building Capacity in STEM Education Research Program (#1937684 & #2200485) and the Research Experiences for Undergraduates program (#2012362 & #1659423). Any opinions, findings, and conclusions or recommendations expressed in this paper are those of the authors and do not necessarily reflect the views of the National Science Foundation. No funding agencies had any role in the design of this study.