This study describes children's early math skills and the kindergarten mathematics content to which they are exposed. The authors focus specifically on teacher survey responses to items about content coverage that align most closely with the content covered on the ECLS-K kindergarten mathematics achievement test. They examine the influence kindergarten mathematics content coverage has on math achievement gains during kindergarten. Finally, they examine how children's level of math skills at school entry interacts with the math content covered in kindergarten. They hypothesize, based on prior research, that children have mastered math skills such as basic counting at kindergarten entry, but that kindergarten teachers continue to emphasize these basic skills. They also hypothesize that children will benefit most from exposure to math content that advances beyond their school entry skills. On the other hand, they anticipate that children in classrooms where teachers teach content that is at or below the skills with which they enter school will gain little to nothing in mathematics during kindergarten. (Contains 4 tables and 1 footnote.)