We give a new proof of Glauberman's ZJ Theorem, in a form that clarifies the choices involved and offers more choices than classical treatments. In particular, we introduce two new ZJtype subgroups of a p-group S, that contain ZJ r (S) and ZJ o (S) respectively and are often strictly larger.Glauberman's ZJ Theorem is a basic technical tool in finite group theory. It plays a major role in the classification of simple groups having abelian or dihedral Sylow 2-subgroups. There are several versions of the theorem, depending on how one defines the Thompson subgroup. We develop the theorem in a way that clarifies the choices involved, and offers more choices than classical treatments.Writing S for a p-group, the following are new. First, we give an "axiomatic" version of the ZJ Theorem, theorem 1.1. Second, for p > 2 we construct ZJ-type groups ZJ lex (S) and ZJ olex (S), which contain ZJ r (S) resp. ZJ o (S) and can easily be larger. Third, we establish the "normalizers grow" property of the Thompson-Glauberman replacement process, and a consequence involving the Glauberman-Solomon group D * (S); see theorems 3.1(v) and 5.4.