This dissertation contributes an interpretation of the ancestral altar tradition among Vietnamese American first and second generation practitioners. It traces the contours of the shifting transformations in domestic religious practice, specifically the transnational and diasporic dimensions in people's lives. I address how and toward what ends the "spiritual" is accessed, experienced and/or transformed in the materiality of everyday life, in the context of a complex relationship to a diasporic homeland and an emerging second generation. The research was conducted in Houston, Dallas, Austin, San Antonio (Texas), Carthage (Missouri), Sài Gòn (Viet Nam) and Pulau Galang (Indonesia). I make two main assertions. The first is that domestic religious practices matter in exploring issues of cultural citizenship and belonging. As a collection of things, I explain how altar assemblages are constituted through the purposeful and chance encounters of the practitioner(s), which is a way to talk about the global (such as transnational mobilities or the discourses about diasporic citizenship) through the intimately local. My second claim is that ideas of cultural citizenship can intersect with religious motivations and practices, and that they happen (are performed, imagined and circulated) transnationally, or more precisely, translocatively. I document how practitioners' and groups of practitioners' struggle to combat the (current Vietnamese) state's interventions in re-narrating the circumstances of their exile and also the relative invisibility they face as historical subjects in the United States. By carefully examining ancestral altars as a constitution of "things" and as situated "spaces," I address various facets of what they are and how they work -- as ways to express a familial or diasporic imaginary; or as assemblages of things that are both intimately meaningful and private, yet situated at the intersections of geopolitical engagements and cultural politics. / text