Leadership for learning has emerged as a framework that subsumes the core characteristics of instructional, transformational, and distributed leadership. Establishing an empirical measurement model of leadership for learning that simultaneously incorporates the perspectives of individual teachers, collective faculty, and principals has been a challenge. Additionally, research for the past four decades has consistently suggested that leadership effects on student outcomes is mediated by numerous school conditions, culture, and staff capacity. This call requires the investigation of the "linkages" among multiple within-school factors. However, the vast majority of quantitative studies regarding school improvement predominantly focused on examining the relationships between two variables, failing to test complex "mediating" relationships among multiple school change concepts. Thus, using the most recent 2018 Teaching and Learning International Survey (TALIS), this three-article dissertation examines the process through which school improvement happens (Study one), why it is important to include both teacher and principal perspectives in measuring leadership for learning tasks (Study two), and the extent to which teacher self-efficacy mediates the relations between leadership for learning practices and teacher outcomes (Study three). The network analysis of study one shows that teacher sense of self-efficacy possesses the highest mediating positions within complex school improvement paths. The four-fold cross-validation multilevel factor analysis of study two establishes a leadership for learning measurement model and suggests the conceptual distinctions in how individual teachers, their collective body, and principals experience leadership for learning practices distributed across the school. The multilevel structural equation modeling analysis of study three suggests that teachers' sense of self-efficacy substantially mediates the relationships between leadership for learning tasks and teacher turnover, equitable teaching practice, and instructional quality. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]