How would you feel if your land had sunk 9 m in the past 50 years because of human activity? It happened in the San Joaquin Valley. In fact, land subsidence has been caused by man’s activities in at least 37 of the 50 states of the United States and affects more than 40,000 km2 in this country alone. Data from a few sites where economic impact is documented suggest a total annual cost to the nation of more than $100 million; worldwide, the total economic impact is astounding and growing. These nine papers, dedicated to Joseph Fairfield Poland's life work, constitute a major contribution to measuring and understanding this problem. They are arranged in three categories: (1) fluid withdrawal from porous media; (2) drainage of organic soil; and (3) collapse into man-made and natural cavities.