This manual provides guidance and documentation for users of the longitudinal kindergarten-second grade (K-2) data file of the Early Childhood Longitudinal Study, Kindergarten Class of 2010-11 (ECLS-K:2011). It mainly provides information specific to the second-grade rounds of data collection. Users should refer to the "Early Childhood Longitudinal Study, Kindergarten Class of 2010-11" (ECLS-K:2011), User's Manual for the ECLS-K:2011 Kindergarten Data File and Electronic Codebook, Public Version" (NCES 2015-074) (Tourangeau et al. 2015), hereinafter referred to as the base-year User's Manual, for information about the general study methodology and the kindergarten rounds of data collection and to the "Early Childhood Longitudinal Study, Kindergarten Class of 2010-11 (ECLSK:2011), User's Manual for the ECLS-K:2011 Kindergarten-First Grade Data File and Electronic Codebook, Public Version" (NCES 2015-078) (Tourangeau et al. 2015) for information about the first-grade rounds of data collection. The first chapter of this report provides an overview of the ECLS-K:2011. Subsequent chapters provide details on the second grade data collection instruments and methods, including a description of how the second grade data collections differ from the kindergarten and first grade rounds; the direct and indirect child assessments; the sample design; weighting procedures; response rates; and data file content, including composite variables.