1 INTRODUCTION
2 DATA
2.1 Star Formation Rates
2.2 Stellar Masses of Bulge and Disk Components
2.3 Total Stellar Masses
2.4 Measures of Environment
2.5 Halo Masses
2.6 Sample Selection
3 METHOD: THE PASSIVE FRACTION
4 RESULTS
5 DISCUSSION
5.1 Comparison to Other Observational Studies
5.2 Potential Theoretical Explanations I: Radio-Mode AGN Feedback
5.3 Potential Theoretical Explanations II: Other Possibilities
6 CONCLUSIONS