This study analyzes the determinants of participation in the off-farm labor supply and the farm labor supply. The farm labor supply patterns of farm operator couples with and those without off-farm labor supply are compared. An endogenous switching regression model is applied to the data of Farm Family Economy Survey 2002. The results are generally in accordance with the microeconomic model of time allocation in the farm family. Age is found to be the most important factor in participation decision in the off-farm labor supply. The length of school education is shown to have significant negative effect on the farm labor supply of male with positive off-farm labor supply whereas its effect on the farm labor supply is not important in case of no off-farm labor supply. For female, age has U-shaped effect on the farm labor supply for those with off-farm labor supply whereas its effect on that of those without off-farm labor supply is reversed U-shapped. The number of children under 6 years has significant effects either on off-farm labor supply participation or farm labor or on both.