This paper expands the theoretical base of intergroup and intercultural communication by testing a new communication model of interdependence (CMII), defined in terms of the embedded nature of groups Giles, M., R. Pines, H. Giles, and A. Gardikiotis. 2018. "Towards a Communication Model of Intergroup Interdependence." Atlantic Journal of Communication 26 (2): 122-130. doi:10.1080/15456870.2018.1432222. Introducing a new visual representation of it, propositions of CMII are tested, by invoking relationships between the U.S. and Canada as they change over time. Relevant self-report outcomes include: social connectedness, language attitudes, and communication accommodation. How awareness of de-interdepending, and whether explicitly invoking the construct 'interdependence' is associated with outcomes, was also examined. Results indicated sufficient support for tenets of the theory to excite future empirical programmatic endeavours.