  Using a recently developed effective field theory for the interactions of
nucleons at non-relativistic energies, we calculate the rate for the fusion
process $p + p \ra d + e^+ + \nu_e$ to leading order in the momentum expansion.
Coulomb effects are included non-perturbatively in a systematic way. The
resulting rate is independent of specific models for the strong interactions at
short distances and is in agreement with the standard result in the zero-range
approximation.
