This correlational study examined the relationships among half-day and full-day public prekindergarten participation and the attainment of social and personal skills, evidenced by the Maryland Model for School Readiness assessment. The chi square test for association was used to test the correlation between the variables and the subgroups of ethnicity (Hispanic), race (Caucasian and African American), and socioeconomic status. A statistically significant correlation emerged; therefore the data were further analyzed using Cramer's V to determine the effect size of the correlation. This study included seven Maryland counties that offered both half-day and full-day public prekindergarten in the 2011-2012 year. Of those prekindergarten students, data were collected from a sample of 3,538 students who participated in either half-day or full-day public prekindergarten. The public extant data were arrayed in the aggregate and then disaggregated by ethnicity, race, and socioeconomic status. Data revealed a statistically significant correlation between half-day and full-day prekindergarten and the attainment of social- and personal-readiness skills. Findings indicated a higher percentage of participants in half-day public prekindergarten programs demonstrated readiness in social and personal skills over those participating in full-day public prekindergarten programs. (author abstract)