OBJECTIVE

Most models of health behavior change applied to condom use behavior have focused on individual differences in theoretical constructs to explain condom use or nonuse, while ignoring the possibility that day-to-day within-person changes in these constructs may contribute to understanding behavior. The goal of the present study was to investigate day-to-day variability in condom use attitudes, self-efficacy, and behavioral intentions and assess the utility of this variability in predicting the likelihood of condom use each day.

DESIGN

A 30-day Web-based structured daily diary was used to collect daily reports of sexual behaviors and data on theoretical predictors of condom use behavior from sexually active college students (N = 116).

MAIN OUTCOME MEASURES

The authors investigated whether condom use attitudes, self-efficacy, and behavioral intentions vary day to day; whether this within-person variability predicts condom use behavior; and whether negative affective states explain this variability.

RESULTS AND CONCLUSIONS

Within-person variability was found for each of the constructs. Within-person day-to-day changes in behavioral intentions and attitudes predicted the instances in which an individual used a condom and daily negative affect partially explained within-person day-to-day changes in behavioral intentions and self-efficacy. Implications for models of health behavior change and for behavior change interventions are discussed.