Socio - economic and environmental impact of Bio Gas Programme with special reference to the Karunapuram and Kanchiyar Panchayaths of Idukki District was undertaken with the support of Kerala Research Programme on Local Level Development, Centre for Development Studies, Thiruvananthapuram. Malanadu Development Society is a Non Governmental Organisation having its headquarters at Kanjirapally, was involved in implementing Biogas Programme since early 1980s. Its area of operation is Kottayam, Idukki and Pathanamthitta districts. The location of the study is Karunapuram and Kanchiyar, two Panchayaths in the Idukki district. Biogas Programme is a spectacular success in Karunapuram Panchayath, while its performance in Kanchiyar was quite dismal. The purpose of the study was to assess the social, economic and environmental impact of the biogas on the adopters on the one hand and to document the experience of MDS in planning, implementing and organizing biogas programme. MDS used a host of simple but innovative techniques to popularize the biogas programme. Its achievement in Biogas nearly comes to one third of the total achievement of the State of Kerala. MDS help ed in simplifying and demystifying Biogas technology. It has contributed substantially to cost reduction of Biogas Programme, thus enabling large-scale adoption even by small and marginal farmers. Biogas has evolutionized both the kitchen and the garden, generating fuel and manure. Women have been the greatest beneficiaries of getting this clean and efficient fuel in the kitchen. The men are attracted more towards the excellent bio manure produced by the biogas plants. The bio slurry is an excellent soil conditioner and immensely benefits the productivity and disease resistance of crops. Bio slurry provides a hope for the windling agriculture in the highrange villages. Though MDS has been successful in the extension aspect of the biogas programme, it is yet to generate sufficient knowledge base to develop learnings and market the learnings for the good of the State. MDS has been concentrating more on the implementation of the programme as an activity and less efforts have been made on generation of knowledge. This is a weakness in its otherwise spectacular and successful programme.