Kenya has a long history of cooperative development and is recognized by the government to be a major contributor to national development, as they are found in almost all sectors of the economy. The Kenya's population participates directly or indirectly in cooperative-based enterprises. According to the government of Kenya, it is estimated that 80 per cent of Kenya's population derives their income either directly or indirectly through cooperative activities. Although significant progress has been made in the establishment of agricultural cooperatives, sustainability is a major challenge for majority of these cooperatives. The performance and sustainability of these cooperatives in Kenya, have been debatable, since the number of cooperatives becoming dormant (have actually closed down) is increasing over time. This study sought to establish the determinants of sustainability of agricultural cooperatives in Kenya. The specific objectives of the study were to examine how managerial skills, access to finance, stakeholder involvement and competitive environment affect sustainability of agricultural cooperatives in Kenya. The study adopted a descriptive design and the target population was 750 staff (senior and middle level management) of agricultural cooperatives drawn from different sub-counties in Machakos County. The sample size for the study was 80 respondents. A stratified sampling technique was carried out by involving all the targeted respondents and primary data was collected through the use of questionnaires. The secondary data was obtained from published documents such as journals, periodicals, magazines and reports to supplement the primary data. A pilot study was conducted for the data collection instrument. The data was with help of SPSS version 21 and Excel. The study adopted a correlation and regression analysis at 5% level of significance to determine strength and direction of the relationship of the variables under study. The regression analysis showed that managerial skills had the strongest positive (Pearson correlation coefficient =.875) influence on sustainability of agricultural cooperatives. In addition, access to finance, competitive environment and stakeholder involvement were positively correlated to sustainability of agricultural cooperatives with Pearson correlation coefficient of .581, .690 and .806 with p-values of .009<0.05, .008<0.05 and .006<0.05 respectively. The study established that managerial skills were the most significant factor. The study recommends for similar studies to be undertaken in other agricultural organizations in Kenya for generalization of the findings of this study.