The purpose of this study was to explore teacher leadership practice in an effort to understand how the behaviors of teacher leaders, and interactions among them, contribute to teacher and collective efficacy for the purposes of increasing student achievement and closing student achievement gaps. Methodology.A grounded theory approach to qualitative research was used to establish a theoretical foundation among the constructs of teacher leadership, efficacy beliefs, and student achievement. Data were primarily collected through an examination of the perspectives of 33 formal and informal teacher leaders in a county in Northern California. Findings.A theoretical framework called teacher leadership for efficacy and equity is proposed, which outlines direct and indirect pathways for teacher leadership to improve student achievement. Teachers who improve student achievement and close student achievement gaps through teacher and collective efficacy (a) focus on equity and improvements to teaching and learning; (b) take ownership over the learning of all students and speak positively about them; (c) build relationships with students and show they care; (d) take initiative, are positive, and go above and beyond; (e) collaborate, use data to inform practice, and share ideas and strategies; (f) learn, mentor, coach, and watch each other teach; (g) are flexible, adaptable, customize instruction, and try new things; and (h) experience and celebrate success and share success with others. These practices are guided and supported by shared leadership, collaboration, and school culture. Conclusions.Existing teacher leadership research supports elements of Facets A, D, E, F, and G of teacher leadership practice. New findings include teacher leaders' maintaining an explicit focus on equity (A), taking ownership over the learning of all students and speaking positively about them (B), building relationships with students and showing care (C), and experiencing and sharing success (H). New findings are supported by research in other areas.Recommendations. Teacher leaders who impact student achievement should be considered teachers as well as leaders. Stronger attention should be paid to informal teacher leadership, teacher leadership practice, and fostering equity through teacher leadership. Recommendations include operationalizing this framework in quantitative studies, putting it into practice, and replicating the study in other contexts.