The ${BP}$-theory of two-fold products of projective spaces Jes\'us Gonz\'alez Departamento de Matem\'aticas Centro de Investigaci\'on y de Estudios Avanzados del IPN M\'exico City 07000 jesus@math.cinvestav.mx W. Stephen Wilson Department of Mathematics Johns Hopkins University Baltimore, Maryland 21218} wsw@math.jhu.edu We compute the BP (co)homology of the product of two (stunted) projective spaces. The behavior under maps (particularly of the Tor term) is studied. This is used extensively by Kitchloo and Wilson in their work on non-immersions. Additional work with lens spaces is also included.