While the question of what makes a journal impactful continues to draw scholarly attention and debate, the lack of conceptual foundation as to what journal impact represents, and how it manifests itself, has impeded efforts to establish a richer understanding. Drawing from the theory of innovation diffusion, we propose journal impact as a multidimensional concept manifested most prominently in the magnitude, prestige, breadth, dispersion, and duration dynamics of citations accruing to a journal. In doing so, we complement extant representations of journal impact as a unidimensional concept with insights into the pattern and profile of a journal impact across space and time. We illustrate the multidimensionality of journal impact as a diffusion process in a longitudinal analysis of citation patterns at the Journal of Management Studies over a 40‐year period.