This study investigates attitudes and motivation that influence heritage and non-heritage students' learning of Chinese as a second language, examining the similarities and differences among three subgroups: bilingual, heritage motivated, and non-heritage learners. The study uses the socio-educational model by Gardner (1985), the internal structure model (Csizer & Dornyei, 2005), and the attribution theory (Weiner, 1985) for the investigation. Participants were 317 students enrolled in Chinese courses at three state universities in the U.S. The results demonstrated that "positive learning attitudes and experience" was the factor most predictive of motivational magnitude (intended learning efforts in the present) and direction (intended continuation of study in future). "Instrumentality", rated very highly across the three subgroups, appeared as the second significant predictor for intended continuation of study in future) with both groups of heritage learners. Although the bilinguals and heritage motivated learners did not differ significantly in most motivational factors, significant differences were observed between the heritage and non-heritage learners on most other factors. Heritage learners, especially Chinese bilinguals, seemed to be more likely to attribute their success in the course to uncontrollable and/or external factors and failure to internal factors. Heritage learners may desire to learn their heritage language (HL) instead of other foreign languages due to socio-cultural influences. Studies of Chinese heritage learners (Chao, 1997; He, 2008) have demonstrated that learners may study Chinese to search for their ethnic identities and recover the roots of neglected cultural heritage. Research (Fishman, 2001; Valdes, 2001; Li & Duff, 2008; Wiley, 2001) also has shown that heritage and non-heritage learners may differ not only in linguistic and cultural backgrounds but also in socio-psychological and affective dimensions. Considerable work has been done comparing the linguistic similarities and differences between HL and non-HL learners of the same language (see Comanaru and Noels, 2009, for a comprehensive account), but much less has examined learners' motivational and affective factors in their second language (L2) learning. The present study investigates attitudes and motivation of heritage and non-heritage learners in learning Chinese as a L2 at the university level in the U.S. (Contains 3 tables, 1 figure and 4 notes.)