https://doi.org/10.1177/0013161X17696556 Educational Administration Quarterly 1–32 © The Author(s) 2017 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0013161X17696556 journals.sagepub.com/home/eaq Article The School Principal and Student Learning Capacity Curt M. Adams 1 , Jentre J. Olsen 1 , and Jordan K. Ware 1 Abstract Purpose: The purpose of this study was to define student learning capacity and to examine the role of the school principal in nurturing it. Method: The study used cross-sectional data from 3,175 students in 70 schools located in a metropolitan area of a Southwestern city. We tested three hypotheses by following a conventional modeling building process in HLM 7.0: Hypothesis 1—Principal Support for Student Psychological Needs (PSSPN) is related to school differences in student-perceived autonomy- support; Hypothesis 2—PSSPN is related to school differences in student- perceived competence-support; Hypothesis 3—Student-perceived need- support mediates the relationship between PSSPN and grit. Results: Evidence aligns with our initial theorizing about student learning capacity and principal support for student psychological needs. Student-perceived need-support, as a social characteristic of capacity, manifests itself through teacher–student interactions in the learning process. Need-supporting interactions varied significantly across schools, and principals played a critical role in developing an instructional environment that students experienced as nurturing autonomy and competence. Implications: PSSPN highlights the transformative effects that regular principal–teacher social exchanges can have on instructional practices. School principals who interacted with teachers about student psychological needs and need-supporting 1 University of Oklahoma, Tulsa, OK, USA Corresponding Author: Curt M. Adams, University of Oklahoma, 4502 E. 41st Street, Tulsa, OK 74135, USA. Email: curt.adams-1@ou.edu 696556EAQ XX X 10.1177/0013161X17696556Educational Administration QuarterlyAdams et al. research-article 2017