The report examines rates of participation in West Virginia's universal, voluntary prekindergarten (PreK) program from 2002-03 to 2006-07. It describes the share of seats provided by collaborative partners and public school systems and analyzes participation rates by demographic and socioeconomic subgroup and county characteristics. Reported findings include: (1) Statewide participation in West Virginia's PreK program rose from 26 percent in 2002-03 to 43 percent in 2006-07; (2) Although in 2002-03 the only documented providers of publicly funded PreK seats under the program were public school systems, in 2006-07 nearly a third of the seats were provided by approved collaborative partners; (3) Participation in the West Virginia PreK program varied by subgroup; (4) Although statistical analysis of participation rates, using multiple covariates to control for other factors, showed that membership in certain demographic and socioeconomic subgroups was not associated with participation in the PreK program, differences in certain county characteristics were associated with PreK program participation; and (5) Some evidence indicates an inverse association between county-wide income levels and PreK program participation rates. Two data limitations are cited: (1) West Virginia Department of Education suppressed its data on PreK program participants wherever there were fewer than 10 participants in a given data cell, weakening conclusions about subgroups; and (2) Data were not available on private PreK program participation or on the use of other early education programs. Based on this report, it is not possible to infer a causal relationship between a particular child, classroom, or county attribute and the extent of participation in West Virginia's universal, voluntary PreK program. Three appendices are included: (1) Research on Kindergarten Readiness and on the Benefits of Prekindergarten; (2) Methodology; and (3) Detailed Results from the Participation Analysis. (Contains 3 notes, 2 boxes, 5 figures and 11 tables.) [For report summary, see ED504869.]