Interpersonal problem-solving ability takes an increasingly important role in the socialization process during childhood. This paper describes the development and preliminary evaluation of the interpersonal problem-solving inventory for elementary school students (IPSI). The IPSI is a process measure structured into five subscales: Positive problem-solving behavior; Negative problem-solving behavior; Rational problem-solving behavior; Impulsive behavior; and Avoidance behavior. The scale was administered to a Vietnamese elementary student sample that consists of 437 third grade students (M = 8.67, SD = 0.47). The reliability of the tool was reported by calculating internal consistencies (Cronbach’s α = .88; McDonald’s ω = .85). The construct validity of IPSI was investigated by using exploratory factor analysis (EFA) to explore the emerging factor structure of IPSI on the first data set. The confirmatory factor analysis (CFA) was performed on the second data set to define theory-driven five-factor structure of IPSI in comparison with any structure emerged from EFA. The CFA findings indicated that the data verified the theory-driven five-factor model of IPSI. The initial testing of the five-factor model showed a moderately good fitting model with four of the five global fit indices (χ2/df = 1.274 < 2, p < .001; CFI: .930; TLI: .926; GFI: .842; and RMSEA: .032 < .05). The results suggest that the scores of IPSI justified adequate internal consistencies and construct/concurrent validities. The IPSI can assess interpersonal problem-solving skills in elementary students. Caution is recommended pertaining to the preliminary evaluation in a Vietnamese third grade student sample.