Controversy continues regarding the mechanism of coronary restenosis. While neointimal thickening was initially considered the major cause, recent studies suggest that changes in arterial size, or remodeling, plays an important or even dominant role in late lumen loss. Moreover, neointimal thickness and remodeling may be interrelated. The field has been complicated by the fact that remodeling analyses have not used consistent definitions or methods. In this editorial we thus describe a quantitative paradigm for remodeling analyses: as arterial plaque or neointima forms in an artery, it is accompanied by luminal encroachment, artery expansion or gradations of either. In this manner, remodeling is generally defined as any arterial size change (enlargement or contraction), independent or dependent of neointimal thickening. Standardization of definitions and quantitative methods may improve understanding of the components of restenosis resulting from artery size changes, neointimal thickening and their impact on lumen size.