This article reports on an extensive survey administered to advanced heritage language (HL) learners to examine their language behaviors, attitudes, and backgrounds. To date, there have been no detailed categorizations of advanced HL learners to guide classroom instruction and curriculum design. Thus the present study is a first attempt to fill this gap by providing a sociolinguistic profile of these speakers, including their identifying characteristics, linguistic needs, and similarities and differences with lower-proficiency speakers. Survey responses indicate that advanced HL learners possess both productive and receptive skills in the HL, always use Spanish at home, are fluent speakers of a standard variety, already have basic academic skills in Spanish, and are therefore primarily interested in perfecting their academic writing skills. (Contains 4 notes and 2 tables.)