This manual provides guidance and documentation for users of the longitudinal kindergarten-first grade (K-1) data file of the Early Childhood Longitudinal Study, Kindergarten Class of 2010-11 (ECLS-K:2011). It mainly provides information specific to the first-grade rounds of data collection. Data for the ECLS-K:2011 are released in both a restricted-use and a public-use version. This manual, which has been developed for public dissemination and use with the public version of the data, is almost identical to the manual released with the kindergarten-first grade restricted-use file. The report begins with an overview of the ECLS-K:2011. Subsequent chapters provide details on the first-grade data collection instruments and methods, including a description of how the first-grade data collections differ from the kindergarten rounds; the direct and indirect child assessments; the sample design; weighting procedures; response rates; and data file content, including composite variables. The ECLS-K:2011 is a multisource, multimethod study that focuses on children's early school experiences. It includes interviews with parents, self-administered questionnaires completed by teachers and school administrators, and one-on-one assessments of children. During the kindergarten year, it also included self-administered questionnaires for nonparental before- and after-school care providers. The ECLS-K:2011 is following a cohort of children from their kindergarten year (the 2010-11 school year) through the 2015-16 school year, when most of the children are expected to be in fifth grade. The sample includes both children who were in kindergarten for the first time and those who were repeating kindergarten during 2010-11. The ECLS-K:2011 K-1 data file includes both the base-year and first-grade data, encompassing both the fall and spring rounds of data collection in kindergarten and first grade. The data are provided on CD-ROM and accessible through software called the electronic codebook (ECB). The ECB allows data users to view variable frequencies, tag variables for extraction, and create an extract file for analysis. Chapter 8 provides specific instructions for installing the ECLS-K:2011 Electronic Codebook (ECB). Two appendixes are included: (1) Data Anomalies and Errata; and (2) Supplemental Guide for the Kindergarten-First Grade Public-Use Data File. [For the general study methodology and kindergarten rounds of data collection, see "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" (ED566378).]