The purpose of this study was to determine if a change from a half day, everyday (HDED) kindergarten program to a full day, everyday (FDED) kindergarten program would result in significant differences in children's achievement. Data on children involved in the first 2 years of the FDED program in the Community Schools District, Grant Wood Area, Iowa, were compared to similar data on children involved in the last 2 years of the preceding HDED program. Data were collected upon entry into kindergarten, at the end of kindergarten, in the spring of the first grade, and in the fall of the second grade. Measures included a Waupun assessment of motor and verbal development and audio and visual perception, Metropolitan Readiness Tests, Gates-MacGinitie Reading Tests, Iowa Tests of Basic Skills, and demographic and school data. An analysis of covariance was used to adjust the outcome measures for initial differences that existed at the start of the study. Results indicated that although the FDED program provided more learning opportunities, these were not reflected in significant differences between the two programs at the end of the kindergarten year. Subsequent findings concerning first and second grade students indicated that their scores became more different from each other both between the years within a program and between the two programs even after initial differences were taken into account. (A bibliography and 11 tables are included.) (Author/RH)