PurposeThe purpose of this paper is to define the integration capability dimensions and create a model for self-assessing the integration capability in inter-organizational projects.Design/methodology/approachA theoretical construct of, referred in this study as integration capability framework is elaborated following a systematic literature review. Thereafter, an integration capability self-assessment model, based on maturity thinking, is derived from the theoretical framework. The self-assessment model is further developed and tested for validity within five inter-organizational project networks in cooperation with industry practitioners, representing construction, industrial engineering, and mining sectors.FindingsThe results show that inter-organizational projects can use the developed model in self-assessing the maturity levels of various integration mechanisms, thus the state of integration capability at any point in time during inter-organizational projects.Originality/valueThis study is an attempt to identify how the integration capability dimensions can be self-assessed in inter-organizational projects, through the maturity levels of various integration mechanisms. The results offer insights for both academics and project management practitioners.