We propose to obtain the most detailed and accurate star formation and chemical evolution histories of two nearby southern dwarf spheroidal galaxies, Fornax and Sculptor, by means of detailed Color-Magnitude Diagram (CMD) analyses of the resolved stellar populations. This requires deep multi-color imaging with CTIO/MOSAIC calibrated to the highest standards to obtain accurate photometry of individual stars down to the oldest Main Sequence Turnoff stars over the entire galaxies. These CMDs will be combined with our spectroscopic surveys of the abundances and velocities of large numbers of individual Red Giant Branch stars in these galaxies. This will allow us to determine accurate time scales for chemical enrichment and thus also for the production mechanisms of different elements in supernovae explosions and stellar winds. We will thus be able to quantify how different processes have affected the evolution of these small systems with time and how they relate to the known stellar population gradients in these systems. We will observe the gradients at the main sequence turnoff level, and thus directly in terms of age. This will result in the most complete picture of the formation and evolution of any galactic system ever made.