As their income was under the poverty line income (PLI), most of the rubber smallholders were listed as hard-core poor with the average earning of below RM800 per month. Regarding this issue, the government and private sector have provided several entrepreneurial programs to improve their better lives but however the participation among rubber smallholders are still low according to RISDA report. Therefore, a study is conducted to evaluate the variables affecting the involvement of RISDA rubber smallholders in Kelantan in agro-entrepreneurship program. Theory of Planned Behaviour (TPB) used to observe attitudes towards people behaviour which is important to determine the factor of participation of rubber smallholders in agro-entrepreneurship program conducted. Attitudes influence behaviour by their impact on intentions while intentions and attitudes depend on the situation and person. Thus, TPB model on data derived from Kelantan rubber smallholders with independent variables such as attitude, subjective norm, and perceived behavioural regulation is applied. The questionnaires were distributed among 100 RISDA rubber smallholders using a simple random sampling technique and the data was analyzed using a descriptive and correlation analysis. Results have shown that the all factors influencing participation have high mean score and was significant to the participation towards agro-entrepreneurship program.