effectiveness, and risk management are vital for enterprises which encounter the pressure to survive in the competitive marketplace. There are assessment tools developed to aid organizations in this regard. In this research an assessment model for collaborative maturity in inter-organizational networks is introduced. We have first investigated collaborative models, conceptual collaborative frameworks and the model for collaborative maturity, “collaborative maturity in inter-organizational networks” and interoperability. After analyzing the maturity models, five levels are resulted; independent, temporary, coordinated, standardized and optimized. Using the “Design Science ” approach and “Meta Synthesis” research methodology, seven dimensions (structural, moral, process, data & information, strategy, systems and innovation) and twenty-five indexes are extracted. In the next stage the proposed model has been assessed based on experts’ opinion. A binary testing has been applied to analyze the questionnaires. All indexes were approved and none were omitted. Using Friedman testing, components of each dimension are then prioritized. Weighted average method has been used to calculate weight of components to determine the final score for each component. Using another questionnaire, we studied Iranian Milk Industry Commercial Company which has had collaborations in Shabab network. The collaboration maturity level in network was between 1 and 2. Finally, based on the literature review, solutions are proposed to achieve higher levels of the maturity and improve the weaknesses of the company.