Despite the presence of several studies on technology adoption, there are limited empirical studies on how socio-psychological factors affect the adoption of sustainable agriculture. Therefore, this paper investigates how socio-psychological factors-such as social capital, information, attitudes, efficacy, and aversion-affect smallholder farmers’ decisions to adopt sustainable land management practices, such as agroforestry systems, organic compost, and crop rotation with legumes. Cross-sectional data are collected from 350 randomly selected farm households using a pre-tested and structured questionnaire. A multivariate probit model is used to investigate factors that influence the probability of adopting these practices. The ordered probit model is also applied to identify and analyze the determinants of the number (intensity) of land management practices adopted. The findings indicate that nearly half of the farmers have adopted these land management practices to improve soil fertility, enhance water retention capacity, and increase productivity. It is also found that attitudes, information, education, group membership, relational capital, risk attitudes, and labor supply significantly affect the probability of adopting these agricultural practices. The estimates of the ordered probit model also indicate that extension services, risk attitudes, group membership, relational capital, education and labor supply are major determinants of the number of land management practices used. However, financial resources, biophysical factors and some demographic factors are found to have an insignificant effect on sustainable agriculture adoption. This implies that when it is necessary to promote sustainable land management practices and to stimulate smallholder farmers to adopt such practices in isolation or combination, specific strategies should be designed to improve awareness, build positive attitudes, reduce risk aversion, strengthen formal organizations, and empower endogenous groups (or informal institutions).