Not all immigrant populations are the same. In this article, we decompose the age-sex structures of immigrant populations in Australia and its major cities in 2021 by periods of entry. The results show a wide array of differences among immigrant populations, as well as across major cities where the vast majority of immigrants reside. Not surprisingly, we find that immigrant groups with a longer history of immigration to Australia have a more varied age-sex profile than those with a shorter history. However, even within each immigrant group, we find substantial differences across cities that reflect the influences of policy and the preferences of the immigrants. By illustrating how historical immigration streams across areas in Australia have produced different population age-sex structures, we are able to better understand why they are different and what specific services they may require.