Background: There is a paucity studies on partners’ discussions about child bearing in Iran. To shed some light on this understudiedsubject, we need to develop a valid and reliable instrument at first.Objectives: To formulate a questionnaire that evaluates the responsible participation of couples in childbearing decision making.Methods: In this paper, a mixed-method sequential explanatory design was used to design the proper instrument. The questionnairewas developed and tested in three stages. In stage 1, an item pool was generated. In stage 2, content validity was assessed andin stage 3, validity (exploratory factor analysis and confirmatory factor analysis) was performed.Results: At the first step, a 13-item instrument was designed, with the results yielding a content validity index of 0.80 for the instrument.The principal component analysis was applied to a sample population consisting of 450 couples to identify the factorstructure of the inventory. According to the results, values of 4.458 (df = 78, P < 0.001) and 0.84 were obtained for Bartlett’s test ofsphericity and Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy respectively. As such, three factors with a total varianceof 62% were extracted, out of which four factors had acceptable reliability with a Cronbach’s alpha of 0.60 to 0.85. The results ofconfirmatory analysis of RPCF questionnaire demonstrated the acceptable fitness of the model (CFI = 0.95 TLI = 0.94 and RMSEA =0.05 and x2/ df = 2.99).Conclusions: Our results showed that the instrument consisted of three dimensions and exhibits high internal consistency. Alsothis study approved the use of RPCFQ to measure responsible participation of couples in childbearing.