Current modalities of sex therapy, consisting of both cognitive-behavioral andsystemic approaches, show moderate results. Yet the very fact that such resultsare at times inconsistent or incomplete indicates that something is lacking intreatment. The present paper suggests that such inadequacies may be a resultof a lack of focus on all aspects of sexuality asbiopsychosociallydeterminedwithin current modalities. The Sexological Systems Model proposes sexualityas a developmental process similar to Bronfenbrenner’s Bioecological SystemsModel. The Sexological Systems Diagram is introduced as an intervention forboth assessment and psychoeducation for couples presenting for sex therapy.Information obtained through facilitating the Sexological Systems Diagram canbe used by the therapist to determine the most appropriate treatment plan.