Objectives: The main purpose of the research was to examine the role of men in decision-making concerning family size, fertility control, motivation to have children and contraceptive use. Specifically, this research examines the role of men in family planning and fertility control in the city of Yazd, the capital city of Yazd province in Iran, which has highest level of male participation on family planning and contraceptive use in the country. Methods: Data used in this study comes from an individual survey interview conducted in Yazd, a city in the central part of Iran. Target population for the study was all currently married men aged 15-49. A total sample size of 296 men was interviewed and used in the present analysis. Participants were questioned about their fertility and family planning attitude and behaviours as well as a range of other socio-demographic variables such as family income, level of their individual modernism, degree of religiousness, use of mass media and so on. Measure of individual modernization, as well as measure of the degree of religiousness also developed and its reliability and validity discussed. Bivariate and multivariate analyses were performed to identify factors associated with role of men in family planning. Findings: Data shows that in our research site men have a high level of participation in family planning and contraceptive use, with 69 percent of men reported that use a male based method to control fertility. Condom with 37.6 percent, withdrawal with 27.9 percent and vasectomy with 3.8 percent are among the most popular method used. The analysis reveals a positive correlation between measure of individual modernization and the use of male methods. The analysis also indicates that male involvement in family planning increase with a rise in male education and decrease with rising age. As analysis shows measure of individual modernization and age explain 11 and 8 percent of dependent variable variance respectively. Altogether, 28.5 percent of variance for male involvement in family planning can be explained using linear transformation variance by such independent variables as individual modernism, religiousness, income, education, age, and influence of mass media. Analysis reveals that individual modernism, religiousness, income and education have significant impact on men's participation on family planning and fertility control. While age and influence of mass media has significant negative influence on male's family planning and fertility control. Furthermore, the results indicated that individual modernism and age enjoyed the most impact on family planning decision and fertility control. Results: The results indicated that role of men in family planning is incredibly high and even more significant than women’s. The results of the study is consistent with diffusion and economic theories of fertility change, shows that individual modernism, religiousness, income and education have significant impact on family planning behavior of men.