The nonabelian tensor square and the Schur multiplicator are determine
d for arbitrary groups of class 2 in a closed form. A functorial descr
iption is given in terms of a polynomial quotient of the integral grou
p ring, as well as a more explicit formula for finite groups which can
be evaluated by matrix calculus. This is carried out for 2-generator
groups. Also some homotopical data of the suspended classifying space
of class 2 groups are derived. The approach is based on the use of pol
ynomial maps and constructions in the sense of Passi. (C) 1996 Academi
c Press, Inc.