Cancer poses a set of physical and emotional challenges to the patient, spouse, and their relationship. One challenge for couples is discussing cancer-related concerns in a manner that facilitates intimacy. Current couple-based interventions have been shown to have mixed efficacy, and little is known about how they bring about improvements. This study aims to expand our understanding of dyadic communication and intimacy to adapt and/or develop more effective interventions for couples coping with cancer. To accomplish this goal, the present study examined affective and behavioral processes associated with intimacy using the valence-affective-connection (VAC) framework and observational coding methods. Participants were 134 couples in which a patient was diagnosed with breast, colorectal, or lung cancer. Couples completed a battery of questionnaires, including a self-report measure of intimacy. Couples also completed a 15-min videotaped interaction about a cancer topic of their choosing, which was observationally coded for communication behavior and affective expression. Couples coping with cancer who reported higher versus lower intimacy engaged in qualitatively different levels, types, and patterns of communication behavior and affective expression. Specifically, couples who reported lower relationship intimacy used negative approach behavior and hard negative affect more frequently and for longer periods of time and were more likely to use avoidance-based communication. Higher intimacy couples were less likely to sustain the use of negative behavior and affect and displayed more reciprocity of positive joining affect. The study highlights important considerations for couple-based interventions and research in the context of cancer. (PsycInfo Database Record (c) 2024 APA, all rights reserved).