A multi-activity DEA model with variable returns to scale is proposed to provide information on the efficiency performance of organizations with inputs shared among several closely-related activities. The model is applied to study the case of 279 farmers’ cooperatives in Taiwan. The results provide overall and individual performance measures for each activity as well as suggestions for future improvement. Inter-firm networking should be strengthened and thus policies that promote the consolidation of TFCs will not be sufficient to meet the public goal of institutional reform.