A new, post-industrial, paradigm for agriculture is emerging under the concept of sustainable agriculture. The sustainability paradigm has emerged to solve problems created by the industrial model, primarily environmental pollution and resource base degradation. The role of farm size in this transformation to a more sustainable agriculture is the issue addressed. Using a descriptive approach, and relying on a survey of the literature including emerging paradigms and observations, we conclude that, from a sustainability perspective, the smallest effective size will be the most competitive size for farms, as for other knowledge-based enterprises of the future.