The notion of heritage language (HL) has recently been challenged by emerging orientations to language. That languages are always in contact, they are constructed by ideologies, and they don’t have an ontological status challenge traditional notions of HL as primordial, pure, and territorialized. In this article, I draw from data from a qualitative inquiry adopting observations, surveys, and interviews on how families of the Sri Lankan Tamil diaspora community in UK, USA, and Canada define heritage language and competence. I focus specifically on interview data to unveil the language ideologies of community members relating to heritage language and identity. For them, competence means having the ability to align Tamil verbal resources strategically with multimodal semiotic resources and spatial repertoires to accomplish social and cultural communicative activities. For this objective, being proficient in fragmentary verbal resources, receptive and/or conversational skills, low diglossic Tamil, and informal register are deemed satisfactory. Therefore the corpus that is considered as HL is also changing in diaspora contexts to accommodate appropriations from other languages, and metonymic uses, which develop shared indexicality for the community. I label these assumptions as constituting a practice-based ideology of HL. Such an orientation will help us understand HL as a socially constructed and changing construct, while affirming its importance for migrant communities.