Hopelessness has become an increasingly important construct in palliative care research, yet concerns exist regarding the utility of existing measures when applied to patients with a terminal illness. This article describes a series of studies focused on the exploration, development, and analysis of a measure of hopelessness specifically intended for use with terminally ill cancer patients. The 1st stage of measure development involved interviews with 13 palliative care experts and 30 terminally ill patients. Qualitative analysis of the patient interviews culminated in the development of a set of potential questionnaire items. In the 2nd study phase, we evaluated these preliminary items with a sample of 314 participants, using item response theory and classical test theory to identify optimal items and response format. These analyses generated an 8-item measure that we tested in a final study phase, using a 3rd sample (n = 228) to assess reliability and concurrent validity. These analyses demonstrated strong support for the Hopelessness Assessment in Illness Questionnaire providing greater explanatory power than existing measures of hopelessness and found little evidence that this assessment was confounded by illness-related variables (e.g., prognosis). In summary, these 3 studies suggest that this brief measure of hopelessness is particularly useful for palliative care settings. Further research is needed to assess the applicability of the measure to other populations and contexts. (Contains 1 figure and 4 tables.)