  Singlet extensions of the Standard Model (SM) allow for a strongly first
order electroweak phase transition, because of trilinear terms in the
tree-level potential. We present a systematic procedure to study the parameter
space of the Next-to-Minimal Supersymmetric SM (NMSSM). We find that this model
is consistent with electroweak baryogenesis for a wide range of parameters,
allowing Higgs masses up to at least 115 GeV.
