  We consider the possibility that the gravitino might be the lightest
supersymmetric particle (LSP) in the constrained minimal extension of the
Standard Model (CMSSM). In this case, the next-to-lightest supersymmetric
particle (NSP) would be unstable, with an abundance constrained by the
concordance between the observed light-element abundances and those calculated
on the basis of the baryon-to-entropy ratio determined using CMB data. We
modify and extend previous CMSSM relic neutralino calculations to evaluate the
NSP density, also in the case that the NSP is the lighter stau, and show that
the constraint from late NSP decays is respected only in a limited region of
the CMSSM parameter space. In this region, gravitinos might constitute the dark
matter.
