EXHIBIT 21 WPL HOLDINGS, INC. AND SUBSIDIARIES SUBSIDIARIES The subsidiaries and affiliates of as of December 31, 1993, are as follows: % of Voting Stock Owned Directly or Indirectly State of by the Name of Subsidiary Incorp. Company A. Wisconsin Power and Light Company Wisconsin 100% 1. South Beloit Water, Gas and Electric Company Illinois 100% 2. REAC, Inc Wisconsin 100% 3. NUFUS Resources, Inc Wisconsin 100% 4. Wisconsin River Power Company Wisconsin 33-1/3% 5. Wisconsin Valley Improvement Company Wisconsin 13% B. Heartland Development Corporation Wisconsin 96.25% 1. Heartland Environmental Holding Company Wisconsin 95.7% A. RMT, Inc Wisconsin 100% 2. Heartland Properties, Inc Wisconsin 100% A. Tool Kit Property Management Systems, Inc Wisconsin 100% B. Heartland Retirement Services, Inc. Wisconsin 100% 3. Capital Square Financial Corporation Wisconsin 100% 4. ENSERV, Inc Wisconsin 100% A. Heartland Fuels Corporation Wisconsin 80% 5. WP&L Communications, Inc Wisconsin 100% No separate financial statements are submitted for any subsidiary since none of these subsidiaries qualifies as a significant subsidiary under SEC rules.