  The construction and analysis of 3d effective theories for the description of
the thermodynamics of the cosmological electroweak phase transition are
reviewed. For the Standard Model and for the MSSM with stops somewhat heavier
than the top, the effective theory is 3d SU(2)+Higgs, and the transition is
strong enough for baryogenesis at no Higgs mass for the Standard Model, and up
to m_H ~ 80 GeV for the MSSM. For lighter stops, the effective theory is
SU(3)xSU(2) + two scalars and the transition could be strong enough up to m_H ~
100 GeV. However, a lattice study in 3d is needed to confirm the last bound.
