Debate surrounds the definition, measurement and utility of subjective norms (theory of reasoned action, Fishbein & Ajzen, 1975; Ajzen & Fishbein, 1980). Scholars propose alternative concepts including descriptive norms and injunctive norms (Cialdini et al., 1990), enabling factors and social embeddedness (e.g. Barrera, 1986), and betweenness to others in a network (Wasserman & Faust, 1994) to explain social influences on willingness to perform a behaviour. This study explores the relative utility and comparability of different social concepts in understanding Namibians' intentions (n=1200) to abstain from sex or to be faithful to one sexual partner. Neither subjective norms nor the five other concepts consistently predict either intentions, although they account for 21% of variance in intentions to abstain and 24% of intentions to have one sexual partner in one region. Conflicting relationships between injunctive and subjective norms exist; stigma surrounding HIV prevention provides some explanation. Campaigns designed to alter norms may benefit from altering stigma simultaneously.