Research study entitled “Knowledge and Adoption of System of Rice Intensification (SRI) technology among farmers in Nagapattinam district of Tamil Nadu” was undertaken to study the profile characteristics of SRI farmers, assess the knowledge and adoption level of SRI farmers. Further it aims to elucidate the constraints faced by SRI farmers and suggestions. The study was taken up in four blocks of Nagapattinam district with a sample size of 120 SRI farmers. Fourteen independent variables with knowledge level and extent of adoption as dependent variables were studied. The respondents were interviewed personally by a well-structured and pre-tested interview schedule. The data collected were coded, tabulated and analysed using suitable statistical tools. The profile of SRI farmers revealed that majority of the respondents were medium aged, educated up to secondary level, medium level of Farming experience, medium level of land holding, medium level of social participation, attended at least one Training. Scientific orientation, Management orientation, Economic motivation, Extension contact, Achievement motivation, Innovativeness, Mass media exposure and Risk orientation were found in medium level. Majority of the respondents had medium level of knowledge followed by the higher level. An overwhelming majority of respondents had knowledge about the weed management practices, nursery preparation, irrigation management, nutrient management and main field preparation. 12 More than half of the respondents had medium level of adoption in the cultivation of paddy under SRI method, an overwhelming majority of respondents were adopted the weed management practices, irrigation management, main field preparation, nursery preparation and nutrient management practices. The incentives provided by the state government to promote the adoption of SRI technology worked well. The variables viz., Educational status, Training undergone, Scientific orientation, Economic motivation, Mass media exposure, Social participation, Extension contact, Management orientation, Achievement motivation, Innovativeness and Risk orientation, showed a positive and significant association with knowledge as well as Adoption. The variables namely, Age and Farming experience had shown negative correlation to the knowledge level and adoption of the respondents at 1 per cent level of significance. The variable Land holding did not show any relation with either knowledge level or extent of adoption. The lower seed rate required more care while transplanting, death of seedlings in between the rows of main field, the high wage requirement of labour, frequent renaming, multiplicity of the programmes, delay in getting subsidy and meeting different officials for getting loan and the technical advice were the major constraints expressed by the SRI farmers. Training the farmers, strengthening the co-operative society, evolving labour saving techniques and designing of labour saving low cost machineries were suggested by the majority of SRI farmers.