Background: The "Service Need Assessment Profile" (SNAP) measures individual functional needs in areas of daily living. It produces a support profile, detailing the time allocations for staff support to assist in each area of need. The "Supports Intensity Scale" (SIS) is a support needs assessment scale designed to provide an objective measure of a person's need for support in medical, behavioural, and life activities. SIS can be used for individualised support planning, clinical judgements regarding support needs, resource allocation and financial planning. The "Inventory for Client and Agency Planning" (ICAP) assesses adaptive and maladaptive behaviours and gathers additional information to determine type and amount of special assistance that people with disabilities need. Method: This study evaluated the construct and criterion validities of SNAP in relation to the SIS and ICAP, using assessment data from 114 individuals with a range of disabilities and levels of severity. Results: Construct and criterion validities were supported for the SNAP by high correlations with SIS, ICAP, and staff estimates of support needs and by its capacity to discriminate between sub-groups in expected ways. Conclusions: The results provide support for the use of SNAP as a support needs instrument. (Contains 3 tables.)