The dissertation is a two-paper investigation of observed naturalistic marital support behavior in a sample of 30 dual-earner middle-class couples with school-aged children who were videotaped in their homes over 4 days (two weekdays, two weekend days). Couples also self-reported on marital satisfaction, job stress, and emotional distress, as well as provided salivary cortisol samples that permitted analysis of diurnal cortisol slopes. Study 1 entails the conceptualization, development, and implementation of a novel observational coding system for naturalistic marital support behavior that provides a comprehensive descriptive analysis of couple support interactions as they unfold in everyday contexts. Analyses indicate that support interactions were relatively rare, predominantly brief (< 30 seconds long), more often solicited than offered, mostly instrumental compared to emotional in content, and overwhelmingly positive versus negative in emotional quality. In addition, patterns were examined among the different support variables; in particular, findings counter the Support Gap Hypothesis and suggest that wives receive more support than husbands, due specifically to wives soliciting more support. Study 2 examines the predictors and outcomes of couple support behavior using the self-reported individual variables and diurnal cortisol slopes. Findings support the notion that emotional distress and job stress predict the support behavior of both spouses. Interesting sex differences emerged, whereby wives' depressive symptoms, wives' job stress, and husbands' neuroticism appeared to have the strongest influence on supportive behavior. However, analyses indicate little evidence for couple support behavior as a predictor of marital satisfaction and diurnal cortisol slopes. The dissertation provides first insights into couple support processes as they spontaneously unfold in naturalistic settings, highlighting the utility of naturalistic observation to shed light on real-life social behavior and its links with health and well-being.