The cohort model: Lessons learned when principals collaborate Lisa A. Umekubo 1,3 • Janet H. Chrispeels 2 • Alan J. Daly 2 Published online: 7 November 2015 Ó Springer Science+Business Media Dordrecht 2015 Abstract This study explored a formal structure, the cohort model that a decen- tralized district put in place over a decade ago. Schools were clustered into cohorts to facilitate professional development for leadership teams for all 44 schools within the district. Drawing upon Senge’s components of organizational learning, we used a single case study design with two embedded units to examine how a district created opportunities for organizational learning through the cohort model. Our findings revealed how this large district gave considerable autonomy to schools and at the same time created a coherent structure that facilitated both system-wide as well as within cohort professional development. The model also supported formal and informal relationships within cohorts and across the district. Our evidence showed how trusting relationships fostered strong collaboration amongst principals and led to higher levels of social capital and intellectual capital, which in turn enabled the schools and cohorts to practice the components of organizational learning. These schools and the district achieved sustained increases in student achievement. Keywords Decentralized Á Intellectual capital Á Organizational learning Á Social capital In organizations, real power and energy is generated through relationships. The patterns of relationships and the capacities to form them are more important than tasks, functions, roles, and positions. -Margaret Wheatley & Lisa A. Umekubo lumekubo@gmail.com 1 Escondido Union School District, Escondido, CA, USA 2 University of California, San Diego, San Diego, CA, USA 3 257 Moss Street, Chula Vista, CA 91911, USA 123 J Educ Change (2015) 16:451–482 DOI 10.1007/s10833-015-9256-2