The purpose of this study was to develop a grounded theory to determine if the affective domain, supported by affective leadership, was prevalent within Alabama's effective middle schools. The objective was to determine if a connection exists between the schools' knowledge, characteristics, and practices relative to the affective domain and produce a theory supporting this premise. The problem investigated addressed the inadequate use of the affective domain in Alabama's public schools. This study was grounded in the real-world experiences of the 36 school leaders representing 14 effective middle schools in the State. The 14 schools rank at the top in promoting student success. In a 21st Century educational environment, the factors affecting students' social and emotional development and learning outcomes are intrinsically enhanced through affective instruction by (1) application of the affective domain, (2) social and emotional learning skill sets, (3) effective leadership styles, (4) school climate and culture, (5) professional development, and (6) student growth and achievement. This qualitative study evaluated school leaders' perceptions of these research factors and school performance data. Based on the evidence, the faculty and staff created supportive teams that provided optimum learning environments; and the instructional leadership profiles supported the prevalence of affective domain learning in most effective middle schools headed by affective leaders. Yet, due to the impact of COVID-19 on students' social and emotional well-being, a greater need exists for affective pedagogy in 21st Century educational environments to enable continued holistic student development. Such learning environments would benefit children in all Alabama schools. [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.]