The wide-spread prevalence of unimproved sanitation technologies around the world has been a major cause of concern for the environment and public health. Public agencies often grapple with the question why the adoption of improved sanitation technologies has been slow. Based on a case study in rural Tanzania, this paper assesses the local environmental conditions and end users’ socio-economic characteristics as drivers of technology diffusion. The assessment relies on a comprehensive framework of sustainability indicators and draws inputs from a survey of 500 households and focus group discussion with 40 environmental health practitioners. Ninety-six percent of the households had toilets, with only 9.4% having improved toilets. Not all recommended technologies were suitable to certain local soil, water and natural resource conditions. The technologies that end users perceived as socio-culturally and economically acceptable were different from those that experts thought to be environmentally and economically sustainable. Lack of education and family economic status drove a wedge between people’s perception and technical prescriptions. On the basis of multi-criteria, aggregate sustainability index, SanPlat and Pour Flush toilets were the top two sustainable technologies. Finally, using a theoretical framework for technology implementation, the paper identifies several existing and potential gaps that may further slowdown the process of technology adoption. Improvement in sanitation in rural Tanzania requires education of people about its health benefits, proper training, and extension of rural health workers. Direct financial incentives could further enhance sanitation practice, hygiene and environmental conditions. The integration of the multi-criteria assessment and implementation framework done in this study should be of interest to other developing countries as well.