This paper describes the development and application of an instrument to measure the relationships between acculturation, ethnicity, second language learning, self-esteem, and academic success among the Hmong student population in United States postsecondary schools. The instrument assessed seven dimensions of acculturation (behavioral, social, linguistic, values, attitudes, and ethnic self-identification) in terms of both orientation toward Hmong culture and orientation toward mainstream American culture. Items were designed to be as culturally appropriate and explicit as possible. The questionnaire was written in English and piloted with high school students. Results of statistical analyses of the measure's reliability and validity are presented in some detail. It is noted that the instrument could be adapted for other immigrant populations. (Contains 73 references.) (MSE)