THE STAGES OF BEHAVIOR CHANGE MODEL has been used to understand a vari
ety of health behaviors. Since consistent condom use has been promoted
as a risk-reduction behavior for prevention of human immunodeficiency
virus (HIV) infection, an algorithm for staging the adoption of consi
stent condom use during vaginal sex was empirically developed using th
ree considerations: HIV prevention efficacy, analogy with work on stag
ing other health-related behaviors, and condom use data from groups at
high risk for HIV infection. This algorithm suggests that the adoptio
n of consistent condom use among persons at high risk can be meaningfu
lly measured with the model. However, variations in the algorithm deta
ils affect both the interpretation of stages and apportionment of pers
ons across stages.