We provide a theory for the dynamics of collapse of flexible polyampholytes (PAs) using Langevin equation. Metastable pearl-necklace structures form in a time scale proportional to N-4/5 (N is the number of monomers). In the late stage of collapse the pearls merge with the largest one growing at the expense of smaller ones (Lifshitz-Slyozov mechanism). The time scale for this process is tau(coll)similar to N. Counterion-mediated collapse of strongly charged polyelectrolytes (PEs) follow a similar route to the globular state. Simulations support the proposed collapse mechanism for PAs and PEs.