1. INTRODUCTION

2. HST OBSERVATIONS OF THE SAMPLE

3. MODEL GRID

4. RESULTS
4.1. Protostellar Morphologies
4.2. Direct Measurements of Cavity Sizes
4.3. Cavity Sizes vs. SED Derived Properties
4.4. The Prevalence of Point Sources

5. DISCUSSION: CONSEQUENCES FOR PROTOSTELLAR EVOLUTION

6. SUMMARY