Abstract The paper deals with the conditions prevailing in the majority of ice plants and makes suggestions in regard to increasing the efficiency of their operation. The variations of the load factor should be considered in selecting the size of boiler. High boiler efficiency depends more upon design and intelligent operation than upon the quality of fuel used. The author condemns the practice of using a Corliss non-condensing engine for the prime mover on account of its large steam consumption when operated at fractional loads. He recommends the uniflow steam engine and the Diesel oil engine. It should be aimed to reduce the auxiliary power to one-half horsepower per ton of ice. Wet compression is preferable to dry. Plate ice frozen from one side takes loo long to freeze solid; cell-plate ice frozen from two sides freezes solid in one-fourth of the time. Several curves illustrate the rate of heat transmission in brine coolers and ammonia condensers. Ice storage is profitable, and with a reasonably large production of ice throughout the year it contributes greatly to the economical operation of the plant. The effects of various features of condenser installations are indicated in several curves obtained from actual cases. The proper means to conserve ammonia are pointed out and the usual bonus systems are outlined.