The Early Childhood Longitudinal Study, Kindergarten Class of 2010-11 (ECLS-K:2011), is collecting information about the early educational experiences of a nationally representative sample of children who were in kindergarten or who were of kindergarten age in ungraded classrooms or schools in the 2010-11 school year. The data collection began in the 2010-11 school year, when the children in the sample were in kindergarten, and will continue through the spring of 2016, when most of the children in the sample are expected to be in fifth grade. This brief report is intended to provide a snapshot of the children in the ECLS-K:2011 cohort who were in kindergarten for the first time in the 2010-11 school year and in second grade 2 years later during the 2012-13 school year. Information is presented on selected child and family characteristics, such as poverty status, parental education, family type, and primary home language, obtained when the children were in kindergarten. Information is also provided on the children's knowledge and skills in reading, math, and science in the fall and spring of second grade, both overall and by the selected kindergarten-year child and family characteristics. For brevity, the selected findings focus on achievement in the spring of the children's second-grade year. Appended are: (1) Survey Methodology and Glossary; and (2) Standard Error Tables.