1. INTRODUCTION

2. SAMPLE AND DATA
2.1. ALFALFA parent sample
2.2. Optical and UV counterparts of ALFALFA HI sources

3. GLOBAL PROPERTIES OF THE ALFALFA GALAXY POPULATION
3.1. Gas and stars
3.2. Star formation properties

4. THE IMPACT OF OPTICAL VERSUS HI-SELECTION
4.1. Construction of control samples
4.2. Comparison of control samples

5. THE HOST HALOS OF HI-SELECTED GALAXIES
5.1. Spin parameters derived from the Tully-Fisher relation
5.2. λ distribution of the parent population

6. CONCLUSION