Studies have shown family planning adoption is likely to be more effective for women when men are actively involved. The transtheoretical model of behavior change was used to examine mens involvement in general contraception and intrauterine device (IUD) use by their wives. The study was carried out in rural Vietnam with 651 eligible participants. Cons of IUD use for men in precontemplation and contemplation/preparation were significantly higher than those in the action/maintenance stages, whereas the reverse was true for pros of IUD. The self-efficacy for convincing wife to have IUD in precontemplation was significantly lower than for those in higher stages. Womens education and ages, spontaneous recall of modern contraceptive method, cons for IUD, and self-efficacy for contraception and for convincing wives to get IUD inserted (or continue use) were significant predictors of mens readiness to accept IUD. Interventions are targeted to reduce cons and increase self-efficacy for IUD use.