1. INTRODUCTION

2. OBSERVATIONS AND DATA REDUCTION  
2.1. Sample Selection - The HETDEX Pilot Survey  
2.2. Mitchell Spectrograph Optical Spectroscopy  
2.3. Ancillary Data  

3. OBSERVATIONAL RESULTS  
3.1. Ly α Velocity Offsets from the HETDEX Pilot Survey  
3.2. Characterization of the $R\approx2500$ Ly α Spectra  
3.3. Double-Peaked Ly α Emission Across Galaxy Samples  

4. COMPARISON WITH Ly α RADIATIVE TRANSFER MODELS  
4.1. The Expanding Shell Model Grid  
4.2. Model Trends  
4.3. Statistical Comparison with Observed Ly α  

5. DISCUSSION  
5.1. Possible Limitations of Our Models  
5.2. Expanding Shells: the Right Model?  
5.3. Other Models  

6. SUMMARY & CONCLUSION