1. INTRODUCTION
2. SAMPLE SELECTION AND DATA ANALYSIS
   2.1. SLACS lenses and SDSS twins
   2.2. Environment measures
3. ARE THE ENVIRONMENTS OF LENSES SPECIAL?
4. ENVIRONMENT AND INTERNAL STRUCTURE OF EARLY-TYPE GALAXIES
   4.1. Alignment of mass and light
   4.2. Mass density profile
5. DISCUSSION
6. SUMMARY AND CONCLUSIONS