Noting the importance of kindergarten for establishing skills critical for school success, especially for today's diverse kindergartners who differ in the extent and types of early care and educational experiences they have had prior to kindergarten, this study focused on the gains in reading skills made by language minority and mainstream (non-language minority) children. Data were obtained from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 (ECLS-K), a nationally representative sample of approximately 22,000 kindergartners enrolled in 1,000 public and private kindergartens. Two research questions were addressed: (1) are there differences in reading skills of mainstream children and two groups of language minority children (from Spanish-language or Asian-language homes); and (2) what gains in reading do children make during their kindergarten year and do gains differ by home language status, or by characteristics of child, family, or school. Findings indicated that in the fall of the kindergarten year, higher percentages of children from non-language minority and from Asian-language homes mastered each of the reading proficiency levels than from Spanish-language homes. In spring of the kindergarten year, children gained reading skills regardless of the home language. Mainstream children and children from Asian-language homes made larger gains than children from Spanish-language homes in beginning sounds, ending letter sound relationships, and reading words. At each SES level, gains differed by the home language. Public-private school differences were evident in both fall and spring. There were no initial differences and no differences in gains made related to whether children attended a full- or part-day program. (KB)