This study explores the principal driven collaborative planning (PDCP) phenomenon occurring at SUN Elementary School. SUN Elementary is located near the border of Washington, DC. Exploring this new phenomenon requires a close look at the relationships among teachers, and the relationship between the teachers and the principal. This study demands a close look into instructional leadership at SUN, the impact of PDCP on lesson planning, and an evaluation of the effectiveness of the PDCP process. The study is qualitative in nature and uses many aspects of grounded theory by Glaser and Strauss (1967). Observations of teachers in their collaborative planning (CP) sessions, and observations of teachers and the principal in their PDCP sessions were made. Teacher and principal interviews were conducted. Data were collected from these observations and interviews. The data were analyzed and findings emerged. The following are some of the findings that emerged from this study. Departmentalization prevents collaboration on curriculum, sometimes. Working together in the CP sessions creates familiarity and teamwork among teachers, and CP makes a difference in lesson planning for most teachers. The function of the pacing sheet is ambiguous to teachers, and the pacing sheet is the agenda for the PDCP sessions. The principal helps teachers with their lessons and provides student support. The vice principal (VP) ensures that PDCP session meetings are held regularly. The principal creates collaborative planning sessions because she wants instructional conversations with her staff, and she creates a master schedule that allows for PDCP and CP meeting times. The principal has staff approval to start PDCP, and she thinks CP and PDCP are successful. Based on this study I predict that principals who implement the PDCP process will effectively monitor teacher planning and provide assistance to teachers and students in a timely manner. Four appendixes present: (1) Observation and Teacher Interview Schedules; (2) Sun Master Schedule 2010-2011; (3) Sun Elementary Pacing Sheet; and (4) Teacher and Principal Questionnaire Instrument.