The purpose of this study was to expose a theory which explains how married persons maintain monogamy. Ten participants were interviewed twice, using a semi-structured interview format, which lasted approximately 45 minutes to one hour and 30 minutes. The interviews were transcribed verbatim. Grounded theory methods of data collection and analysis were used. Member-checking, bracketing, peer-review, analytic memos, and external auditing were used throughout the study for verification purposes. Participation in the study was based on the inclusionary criteria of: (a) being legally married in the United States, (b) being 18 years or older, (c) having never cheated (i.e., emotionally or sexually) in their current marriage, (d) being able to read and speak English, and (e) being willing to be interviewed twice. The data supported the finding that monogamy is maintained by small, continual, and consistent efforts in each protective factor area. The protective factors include: (a) practicing congruence; (b) fostering values and beliefs which support monogamy; (c) building a secure attachment or emotional bond; (d) sex in a marriage; (e) behavioral, cognitive, and relationship boundaries; and (f) coping individually and as a couple. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]