This paper analyzes and criticizes recent work on gravity models with respect to form, structure, derivation, and theoretical and methodological grounds. The evolution of the model is summarized and a general form is defined. The models are compared as regards certain structural properties — biproportionality, scale, endogeny, consistency, and spatial interaction. The various macro and micro approaches to deriving or interpreting gravity models are reviewed. Problems and limitations of each approach are noted, and their basic theoretical foundations are criticized. Finally, the general trend of gravity model development is discussed.