Cellular proliferation following retinal reattachment surgery frequently results in contraction and subsequent recurrent detachment of the retina, negating an initial successful reattachment. This process has been called by a variety of names, such as massive vitreous retraction, massive preretinal retraction, and, more recently, proliferative vitreoretinopathy. Although a good start has been made by the Retina Society to classify the various types of proliferative vitreoretinopathy, some modifications in the classification are required. The fundamental problem in the treatment of proliferative vitreoretinopathy is a lack of knowledge regarding the factors that stimulate the proliferation of cells. The vitreoretinal surgeon should recognize in the life cycle of this process that stage which an eye with retinal detachment has reached. If there is no active cellular proliferation, then a scleral buckle will usually suffice. If there is traction from epiretinal membranes which cannot be relieved by a buckle, then vitrectomy and adjunct procedures are necessary. If there is active cellular proliferation and epiretinal membranes, then the arguments related to proper timing of vitrectomy must be considered. In cases where the retinal holes can be identified and closed, scleral buckling may be performed with subsequent delayed vitrectomy. In most cases, in my experience, a combination of revision of the scleral buckle is required at the time of vitrectomy and membrane segmentation for proliferative vitreoretinopathy. Until such time as drugs are available to inhibit cellular proliferation or until our basic understanding of the cell biology of this process allows other means of pharmacologic intervention, mechanical approaches will remain necessary for the treatment of the most advanced cases.