This study examines the first four years of Tennessee's Voluntary Prekindergarten program, directed to four-year-olds eligible for free or reduced-price lunch. It reviews participation levels and trends for the program as a whole, for collaborative partner classrooms, and for student and district subgroups and discusses the geographic distribution of program sites. Key findings include: (1) From 2005/06 to 2008/09, the number of PreK program participants increased from 6,943 to 18,746, the proportion of eligible children participating increased from 18 percent to 42 percent, and the proportion of local education agencies participating increased from 83 percent to nearly 99 percent; (2) The number of participants at collaborative partner classrooms increased from 1,428 (21 percent of all participants) in 2005/06 to 3,621 (19 percent) in 2008/09. Collaborative partner classrooms consistently accounted for approximately 21 percent of total PreK program classrooms; (3) PreK program participation levels and rates increased for all subgroups examined but exhibited varying growth rates across student and district subgroups. The participation rate increased faster for racial/ethnic minority students than for White students. Participation rates among students in special education increased from 8 percent to 32 percent. Large districts had fewer participants and lower participation rates than did small districts. Rural districts had higher levels and rates of participation than did nonrural districts. And the percentage of participants enrolled in collaborative classrooms was higher for racial/ethnic minority students and students in nonrural districts; and (4) The majority of public PreK program sites were in the four major urban areas of Tennessee: Chattanooga, Knoxville, Memphis, and Nashville. Collaborative partner sites were more evenly distributed across rural and nonrural areas. Appended are: (1) Literature review; (2) Background on Tennessee's Voluntary Prekindergarten program; (3) Data sources and methodology; (4) Participation by all four-year-olds in the state; and (5) Maps of public school and collaborative partner sites for Tennessee's Voluntary Prekindergarten program, 2005/06-2008/09. (Contains 3 boxes, 12 figures, 6 tables, 14 maps, and 3 notes.)