The intent of this study was to determine if attendance in a good quality prekindergarten program using developmentally appropriate activities had a positive effect on kindergarten mathematics readiness skills and achievement. Participating were 80 children, 4 to 6 years old, divided into two experimental and two control groups. Standardized test scores from the Slosson Kindergarten Readiness Test and the Metropolitan Assessment Package were used to compare the two groups. Each of the experimental groups attended one year of developmental prekindergarten, whereas the control groups had no preschool experience. The results indicated that the experimental groups scored significantly higher than control groups, suggesting that attending preschool had a positive effect on kindergarten mathematics readiness skills and achievement. (Contains 50 references.) (Author/KB)