Land degradation has reduced agricultural productivity in Nepal’s Terai. This has raised concern over the viability of conventional agriculture of the Terai farming system. Agroforestry can be a potential solution to the above problem. This paper aims at identifying socio-economic biophysical and institutional factors affecting the adoption of agroforestry with respect to conventional agriculture. Data were collected from a survey of 288 households through a face-to-face interview. A multinomial logistic regression (MNL) was run with conventional agriculture as a base category. It was found male-headed households were more likely to adopt agroforestry. Having an off-farm income source was positively associated with the adoption decision of farmers as it provides a safety net in case of crop failure. Landholding size was found as a major constraint to adoption. Therefore, smallholder farmers were reluctant to adopt Agroforestry as sparing a part of farmland for tree planting means reducing field crop production and thus failing to meet their annual food demand. Some other variables affecting positively include livestock herd size, provision of extension service, home-to-nearest government forest distance, farmers’ group membership and awareness of farmers about environmental benefits of agroforestry. Irrigation was another constraint that has stopped farmers from promoting the tree-based farming systems. The households with means of transport and with larger family (household) size were found to be reluctant towards agroforestry adoption.