This dissertation examines how a team of five elementary mathematics teachers and their administrators engaged in the iterative process of Lesson Study for professional development over the course of a year. I use Andzaldua's conception of conocimiento, reimagined for math teacher learning by Gutierrez, to analyze data and understand the ways this team of teachers co-created knowledge together. I used embedded Case Study design as outlined by Robert Stake, to look closely and responsively at teacher learning throughout the year. Teachers taught kindergarten to 8th grade mathematics. My fieldwork took place over 9 months, one school year, in a mid-sized Chilean town. Teaching experience in the team of teachers ranged from 2 years to 11 years, with an instructional coach (UTP) with 30 years of experience. Data includes recordings from planning meetings, public lessons/lessons, reflection meetings, focus groups and several sets of interviews including member checking interviews. Participant observations and artifacts from teacher notes and student work in the lessons was also captured and coded with themes of conocimiento/conocimiento. My analysis of the data shows how solidarity in the community of teachers provided obstacles and opportunity to engage in meaningful Lesson Study discussion. [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.]