This volume presents a scientific and practical trend in lifelong education, which focuses on "human activity." This trend is particularly apparent in French speaking countries where a seminal tradition of ergonomics, born in the middle of the 20th century, produced studies about work and workers activity in various contexts. Results demonstrate that working activity, firstly, is always complex, creative and enigmatic despite the efforts done by the designers to create prescribing working environments and by managers to control production procedures, and secondly, cannot be understood...