This study ascertained cassava farmers' attitude towards participation in Root and Tuber Expansion Programme (RTEP) in Delta State, Nigeria. Multistage sampling procedure was used to select 120 respondents from the 3 Agricultural Development Programmes (ADPs) zones in the study area. The study was conducted from June to November 2018. Data on respondents' socio-personal characteristics, income earned from cassava production and attitude towards participation in RTEP were generated using structured interview schedule. Frequency count, percentage, mean, Chi-square, Pearson Product Moment Correlation (PPMC) and multiple regressions were used to analysed data at p ≤ 0.05. The mean age, years of formal education and household size were 46 years, 9 years and 6 persons, respectively. Majority (85.8%) of the respondents were married with formal education (73.3%) and using family labour (37.5%). Most (60.0%) of respondents were cosmopolitan with more than once a week visit to urban centres, while 79.2% earned an average annual income of N234,641.67 from cassava production. A little above average (51.7%) had unfavourable attitude towards participation in RTEP. Age (β=-0.08), household size (β= 0.37) and income earned from cassava production (β= 5.47) were significant contributors to attitude towards participation in RTEP. This study concluded that the attitude of cassava farmers towards participation in RTEP in Delta State is marginally unfavourable and determined by age, household size and income. Therefore, it is recommended that government, development organisations and other stakeholders implementing the RTEP should organize intervention to increase income earned from cassava production, this will enhance favourable attitude towards towards RTEP.