During the past twelve years, ready mixed concrete has proved the most popular material for pool construction. Cast-in-place and pneumatically applied concrete has accounted for about 85 percent of all pools built. The durability and beauty of concrete are two reasons for this. Another is the infinite variety of shapes into which concrete can be molded. Forms for pools should be set for casting walls at least 8 inches thick; floors should be at least 6 inches thick. Small pools can be cast monolithically while larger pools will require expansion and construction joints. The walls in the deeper parts are placed first and the bottom of the inside forms left open. The concrete is dammed until it stabilizes and the excess mix is used to begin the curve in the floor. Concrete for the floor is dumped directly into the excavation, spread with shovels, and worked in with the concrete at the base of the walls. The corners will have about an 8 inch build up. After the forms are removed and the plumbing completed, the walls should be trimmed. At this point, the skimmer opening can be cut in, if it was not provided for earlier by a wooden frame fitted between the forms. Equipment to keep the water clean is fitted in the skimmer opening. The pool is then backfilled and the placing of the bond beam completes the construction. Pneumatic application is believed to account for about 60 percent of the pools constructed with concrete. This technique requires forms only for the bond beam. The reduction in formwork represents a considerable saving in labor and materials, but this advantage is at least partially offset by the special equipment and the skilled craftsman required to do the job. Pneumatic application should be limited to soils that can be shaped the contour desired and which will retain the shape until the work is completed.