[en] An important initial step in the construction of a field theory is to prove that the Hamiltonian (with cutoffs in momentum and the interaction volume) is bounded below by a constant proportional to the interaction volume, uniformly in the momentum cutoff. The result is that this is the case for a class of model field theories in two space-time dimensions known as ''generalized Yukawa₂'' (+-anti psi psi phi/sup N/ + phi/sup 2M/, M > N). The quantity [exp-TH] (H is the Hamiltonian and T > 0) is expanded by a partly renormalised type of perturbation expansion. The expected divergence of the usual perturbation series is avoided by using an approximate (logarithmically divergent) lower bound, derived from Glimm's dressing transformation, to truncate the series. The terms in this expansion are estimated by rewriting the boson fields as Nelson fields; the total Fock space is regarded as fibered over Nelson space and the fermion fields are removed by taking operator norms in the fibres. The resulting expressions involving only boson fields can be estimated by standard methods. This leads to an estimate on [exp-TH] and thence, a lower bound for H