This thesis explores how upward social mobility impacts on the racial and class cultures of Mapuche indigenous people with higher education in Chile, and how this affects their social identities. The research focuses in particular on a sample of socially mobile Mapuche, the biggest indigenous group in Chile, who have managed to achieve a university education and experienced some degree of upward social mobility in their subsequent occupations. This experience of social mobility is often challenging and creates cultural and social tensions, which requires the complex negotiation and renegotiation of identity. Methodologically, this research adopts a qualitative perspective, examining the life trajectories of the respondents in order to explore the challenges that social mobility creates for groups who are disadvantaged in terms of both their class and ethnic position, and examines how my Mapuche sample negotiated their mobility transitions using a variety of different strategies. It is built on data collected through interviews with a group of 40 educationally mobile Mapuche people who live (i) in the Metropolitan region, where the capital city Santiago is located, or (ii) in the predominantly rural Araucania region in southern Chile, which historically was part of the Mapuche homeland. The interviews were focused on highlighting their most significant educational and work experiences in their life trajectories. The argument of this thesis contributes to the understanding of social mobility of indigenous groups from a multi-dimensional perspective, examining how mobility affects both class and ethnic social positioning. In order to understand this, I use a Bourdieusian framework to analyse the process of social mobility transition. The Bourdieusian approach is particularly useful for understanding a key empirical theme that emerges in the sample mobility experiences, in which they narrate the difficulties of transition as leading to feeling like a fish out of waterin their new social locations. However, a cultural class approach does not sufficiently address the intersectional influence of ethnicity on mobility processes, so I also use a more intersectional analysis to explore how, within my sample, people deployed several strategies in order to negotiate mobility transitions and to fit in to their new social location. I show that the participants faced considerable difficulties and disadvantages during their attendance at university, but despite these difficulties they all experienced some degree of upward social mobility. However, their experiences of mobility meant that had to face the tensions of racism as well as class and ethnic boundaries which meant that they had to renegotiate not only their class but also their Mapuche identities. I argue that we can see three main different types of responses, dividing the respondents into three groups: the mobile accommodators, the rooted and re-signifiers. For the mobile accommodators and the rooted, their class identities become their dominant identities but in divergent ways (with the mobile accommodators adopting middle-class identities, whereas the rooted stressed their working-class origins). For a third group, the re-signifiers, their indigenous identities became their dominant identities often with a renewed and politicized focus on their ethnic positioning. These widely varying responses to the experience of mobility show the complexity and dynamic nature of how people manage their identities in processes of transition. I argue that it is necessary to move beyond both conventional as well as cultural class accounts of social mobility because such approaches cannot properly take into account the additional dimension of ethnic identity transitions which are necessary to fully understand the social mobility experiences of my Mapuche sample. Furthermore, such an analysis requires a post-colonial perspective to take into account the complex positioning of the Mapuche people within Chilean society. I therefore also argue that it is necessary to understand the process of social mobility from a decolonial perspective.