Atmospheric aerosols adversely affect human health and alter the earth’s radiative energy balance. With the overall goal of better understanding how anthropogenic emissions affect aerosol formation from gas-phase precursors, my dissertation includes the development and validation of a method to quantify organosulfates and the application of these measurements in tracer-based source apportionment modeling. This study indicates that the organosulfates improve the ability of tracer-based positive matrix factorization model to resolve aerosol formation pathways.