Considering the increase in waste production, scarcity of land allocated to landfill in urban areas, concerns about ecological damages caused by hazardous waste and damages done to the environment, municipal waste management has become of tremendous importance. The study investigated the behavioral patterns of households regarding waste separation at source using data collected through interviewing 391 households in Mashhad in 2013. Tobit model and Heckman two stage model were used. Analysis of marginal effect of variables in Probit model revealed that views about effect of separation of waste in city cleanness had positive effect and economic incentives had negative effect on decisions to Separate paper, glass and wet wastes. The variable of having garden in the house had a positive effect and indirect cost of paying those who collect the waste and family income had negative effects on decisions to separate wet waste from dry ones.Also, the analysis of linear regression (second stage) showed that the views about the effect of waste separation in city had a positive effect on the amount of wet waste separation, and indirect cost of paying those who collect the waste and family income had a negative effect on it. Based on the findings, in order to increase waste separation by households, it is recommended that the policy makers should consider providingthe households with the information about environmental issues regarding waste and how to correctly separate recyclable waste, establishing motivational mechanisms to decrease waste production and increasing households' participation in waste separation.