Melbourne's linguistic and cultural diversity has continually changed in response to global economic forces and shifting patterns of war and conflict. Immigrant and refugee communities have arrived with different skills, educational and professional profiles, and cultural and religious values. The ecological niches of three contrasting linguistic communities in Melbourne are explored to reveal the diversity of the immigrant experience. Demographic changes over the 10-year span of the 1996, 2001 and 2006 censuses are outlined, in relation to groups which differ in migration vintage, size, socioeconomic factors, migration type, and linguistic and cultural distance from the mainstream. The study looks at speakers of Italian, Vietnamese and Sudanese languages, outlining some key demographic factors, and reflects on the lived experiences of members of these groups, as revealed in focus group interviews. The analysis attempts to tease out the commonalities of the urban migrant experience, and also identify ways in which ecological factors make each group unique. The focus is on elements of what Mufwene has called the external ecology of the varieties (i.e. socioeconomic and ethnographic environments, contact setting and power relations).