This cross-sectional study examined perceptions of spousal negative behaviors in 219 cancer patients. A mediational model was proposed to explain why a spouse might respond negatively to an ill partner because of greater restriction on activities as functional impairment increases. A moderating effect of the spouse's marital satisfaction assessed 3 months before other study measures was also proposed. Results provided support for the proposed model. The relationship between increasing patient functional impairment and spousal negative behaviors was medicated by greater restriction in spouse activities, as well as spousal negative mood. A marginally significant moderating effect for marital satisfaction was found. Although these results must be replicated with a prospective study, the findings begin to shed light on why spouses might respond in negative ways to an ill partner.