Biological factors, attachment styles, socioeconomic status, and religion are among some of the variables researched as casual factors of infidelity. However, limited research is available for infidelity originating online. This study aimed to investigate causal factors for engaging in online infidelity via social networking site use. A cognitive behavioral perspective guided the research. Review of literature on offline infidelity, online behavior, and Davis' work on generalized problematic internet use identified the variables relationship satisfaction, impulsivity, permissive sexual values, and the intensity of social networking site use for exploration. Research questions addressed any contribution these four variables may have to engaging in online infidelity. A cross-sectional online survey including the Relationship Assessment Scale, Barrett Impulsivity Scale, Brief Sexual Attitudes Scale, and Problematic Internet Use Questionnaire targeting individuals 21 years of age and older, who reside in the United States, as well as, the U.S. Virgin Islands was available to the public. 136 respondents completed the survey. The study identified relationship satisfaction, rather than relationship dissatisfaction, as the primary predictor of engaging in online infidelity. Additionally, a stronger presence of permissive sexual values was associated with an increase in relationship satisfaction. Those attempting to engage in online infidelity, a group not previously researched, is predicted by impulsivity. The findings from this study can be used by individuals and professionals alike for improving individualized therapeutic practice. The research findings indicate future research in respect to online infidelity, social networking site use, and the population of individuals that attempt to engage in infidelity would be beneficial.