The purpose of the study was to identify the beliefs that underlie farmers’ decisions to engage in agro-forestry, defined as intension to plant trees in the farms. The less proportion of forest land and perpetual degradation of existing forest plantation are confronting serious threats to the sustainability of forest plantation in Pakistan. Agro forestry has been identified the most feasible solution; especially in irrigated areas of Punjab. The application of theory of planned behavior during the survey of 64 farmers in three different ecological zones showed/depicted that farmers’ willingness to plant trees on their fields is a result of their attitudes towards the advantages and disadvantages of trees, their perception of the opinions of salient referents and factors those encourage and discourage farm level tree planting. Farmers’ viewed farm forestry as economically beneficial and environment friendly. Tree planting was being perceived as increasing income, providing wood for fuel and furniture, controlling pollution and providing shade for human and animals. Farmers viewed the hindrance in agriculture operations and the harboring of insects pests and diseases as negative impacts of tree planting; however, they were outweighed by their perceptions of positive impacts. Tree growing decisions of the farmers were influenced by the opinions of the family, owners/tenants, fellow-farmers. Farm forestry programs are more likely to be successful, if they acknowledge and address the factors, which underlie farmers’ reasons for planting or not planting trees.