Head Start is a national program that aims to promote school readiness by enhancing the social and cognitive development of children through the provision of educational, health, nutritional, social, and other services to enrolled children and families. The program places special emphasis on helping preschoolers develop the reading, language, social-emotional, mathematics, and science skills they need to be successful in school. It also seeks to engage parents in their children's learning and to promote their progress toward their own educational goals (Administration for Children and Families [ACF] 2017). It also offers supports related to children's home or Native language and culture based on community needs and priorities. The Head Start program aims to achieve these goals by providing comprehensive child development services to economically disadvantaged children and families through grants to local public and private nonprofit and for profit agencies. To date, the Head Start Family and Child Experiences Survey (FACES) has been a major source of descriptive information on Head Start and preschool children ages 3 to 5 years old who attend the program, with the most recent round in 2014. In 2015, a new study--the American Indian and Alaska Native Head Start Family and Child Experiences Survey (AI/AN FACES 2015)--focused on Region XI, which are programs operated by federally recognized American Indian and Alaska Native tribes. AI/AN FACES 2015 is the first national study of Region XI AI/AN Head Start children and their families, classrooms, and programs. The study presents a new opportunity to explore the psychometric performance of commonly used measures of preschoolers' cognitive and social-emotional development. This technical report describes the performance of cognitive and social-emotional measures of preschoolers' development for AI/AN children, using recent data from AI/AN FACES 2015 and FACES 2014. The purpose of this technical report is to present findings from analyses of how preschool cognitive and social-emotional measures performed in AI/AN FACES 2015. The authors examined the internal consistency of measures when administered to AI/AN children, reviewed descriptive statistics as context of difference in mean ability across groups in the AI/AN FACES 2015 and FACES 2014 samples, conducted analyses of differential item functioning (DIF) within cognitive measures to compare the performance of AI/AN children and White children (including data from FACES 2014), and examined the strength of bivariate correlations between measures of similar constructs and different constructs to assess evidence of concurrent and discriminant validity. The findings, therefore, provide initial evidence on the reliability and validity of the measures for AI/AN preschoolers.