  We present a method to determine the star formation history of a mixed
stellar population from its photometry. We perform a chi-squared minimization
between the observed photometric distribution and a model photometric
distribution, based on theoretical isochrones. The initial mass function,
distance modulus, interstellar reddening, binary fraction and photometric
errors are incorporated into the model, making it directly comparable to the
data. The model is a linear combination of individual synthetic color-magnitude
diagrams (CMDs), each of which represents the predicted photometric
distribution of a stellar population of a given age and metallicity. We present
extensive tests of the algorithm, using both simulated and actual photometric
data. From a preliminary application of the algorithm to a subregion of the
Large Magellanic Cloud (LMC), we find that the that the lull in star formation
observed among the LMC's cluster population between 3 and 8 Gyr ago is also
present in the field population. The method was designed with flexibility and
generality in mind, and we make the code available for use by the astronomical
community.
