Tate cohomology in commutative algebra. J.P.C.Greenlees Journal Pure and Applied Algebra (to appear 1994) \begin{abstract} We construct local Tate cohomology groups of an $A$-module $M$ at a finitely generated ideal $I$ by splicing together the Grothendieck local cohomology groups with the local homology groups of Greenlees-May. We give two quite different means of calculating them, show they vanish on $I$-free modules and prove that many elements of $A$ act invertibly. These local Tate groups have applications in the study of completion theorems and their duals in equivariant topology. \end{abstract}