Strikingly apparent within the demographics of New England, Portuguese is a language rich in standard and nonstandard varieties. In studying Portuguese, it is common for some students to acquire language more easily than their peers, despite receiving the same linguistic input, and others display negative attitudes toward their instructor's variety. Do these attitudes affect learning outcomes? The dearth of research on this topic begged the research question of how language variety affects motivation in adult learners of Portuguese. This study used semi-structured interviews of 20 undergraduate college students with family originating in Brazil or the Azores who sought to learn their families' Brazilian or European Portuguese. Aspects of adult learning, the L2 motivational self-system, and second language acquisition theories were used as theoretical frameworks. I found strong overlapping themes of identity, attitudes, and ideal selves regarding the study of Portuguese varieties in relation to motivation and language acquisition success. Their profound influence on learner motivation was examined, particularly in connection with moments of language and identity crises within the classroom and how participants used Portuguese variants as ethnic or heritage identity markers. The findings suggest language variety relates to ways learners construct identity within their lived, on-going, and fluid life experiences and community settings and interact within cultural contexts. As such, the study recommends language instructors place greater importance on considering linguistic variety in the classroom when assessing adult heritage learners, particularly if they are not teaching the variety those students are motivated to learn. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]