During the past 20 years, understanding of water conserving behavior has improved. Better and more thorough analyses have shown who participates in conservation programs and why, as well as how much water can be saved as a result of programs. This paper addresses participation and penetration rates and their effect on a residential retrofit project in Tampa, Florida. Both participation and retention rates play key roles in program planning, water savings, and cost effectiveness. Programs that achieve the highest possible installation rates should be targeted and effective follow-up should be conducted to ensure that the water saving devices remain installed.