Abstract
The problem whether the sol-gel transition is accompanied by singularities in the free energy is investigated. Two kinds of gels are considered, the weak and the strong gels. In the former case the cross-links are 'annealed', while in the latter they are 'quenched' or permanent. It is found that the 'annealed' free energy has no singularity while the 'quenched' free energy has a singularity at the percolation threshold, given by the elasticity critical exponent.