J.P.C.Greenlees ``Rational torus-equivariant stable homotopy I: calculating groups of stable maps.'' (22pp) This is the first in a series designed to give a complete algebraic model for rational G equivariant cohomology theories for an r-torus G. It constructs an abelian category A(G) of injective dimension r designed to capture localization and inflation information about cohomology theories. The category A(G) is the target of a homology theory on G-spectra, and there is a finite Adams spectral sequence for calculating maps of rational T-spectra for a torus T, with E2 term an Ext in the abelian category. [The distribution of material between Part I and Part II has been substantially reorganized, to the great benefit of readability. However the mathematical content is unchanged (31/8/01).] (27/7/01; reorganized version 31/8/01)