Background: Functional analytic psychotherapy (FAP) is a contextual behavior therapy that targets idiographic behaviors relevant to interpersonal functioning. FAP often targets issues with intimacy, defined as behavior exchanges that are vulnerable to interpersonal punishment. While existing measures examine similar constructs to FAP?s conceptualization of intimacy, the literature lacks a FAP-consistent self-report measure that adequately captures intimacy-related behavior with the capacity to assess behavior change and aid in clinical outcome research. Method: The Functional Analytic Psychotherapy Intimacy Scale (FAPIS) is a 14-item measure developed for both clinicians and researchers to assess intimacy-related behavior. Utilizing two samples of undergraduate students, exploratory and confirmatory factor analyses were conducted, supporting factorial validity of the FAPIS. Results: Reliability tests, including internal consistency and test?retest reliability and construct validity were assessed, providing further support for the psychometric properties of the FAPIS. Conclusions: The FAPIS appears to be a psychometrically sound measure of intimacy that could assist in future FAP-related research. Further research should also assess the FAPIS for clinical utility.