The purpose of this paper is to outline the alignment and differences in the definitions of homelessness between the Australian Institute of Health and Welfare’s (AIHW) Specialist Homelessness Services Collection (SHSC) and the Australian Bureau of Statistics’ (ABS) Census of Population and Housing (the Census). The paper describes key concepts and derivation code logic of both collections. The SHSC collects information about people who seek assistance from, or are referred to Specialist Homelessness Services (SHS) agencies. Data is collected about people who are either homeless or at risk of homelessness and the services provided to these people. SHS agencies receive a particular program of government funding and continuously collect information about their clients, submitting data to the AIHW monthly. The Census is undertaken every 5 years and counts every person and household in Australia on a given night. The information collected in the Census is used to identify all people in Australia who are homeless at that time.