A variety of evolutionary sequences of models for the solar interior has been computed, corresponding to variations in input data, to obtain some idea of the uncertainties involved in predicting a solar neutrino flux. It is concluded that the neutrino flux can be estimated to within a factor of 2, the primary uncertainty being the initial homogeneous solar composition; detailed results are given. With a preferred value of the heavy-element-to-hydrogen ratio Z/X = 0.028, the helium content necessary to fit a model to the observed solar luminosity is found to be Y = 0.27.
