Exhibit 21.1 SUBSIDIARIES OF WAUSAU PAPER CORP. (dagger) 1. Rhinelander Paper Company, Inc., a Wisconsin corporation 2. Wausau-Mosinee International, Inc., a U.S. Virgin Islands corporation 3. Wausau Papers of New Hampshire, Inc., a Delaware corporation 4. Wausau Papers Otis Mill Inc., a Delaware corporation 5. Wausau Timberland Company, LLC, a Wisconsin limited liability company 6. Mosinee Paper Corporation, a Wisconsin corporation Subsidiaries of Mosinee Paper Corporation: (a) The Sorg Paper Company, an Ohio corporation (i) The Middletown Hydraulic Company, an Ohio corporation (b) Mosinee Holdings, Inc., a Wisconsin corporation (c) Bay West Paper Corporation, a Wisconsin corporation (d) Wausau Paper of Minnesota, LLC, a Wisconsin limited liability company (e) Mosinee Timberland Company, LLC, a Wisconsin limited liability company (dagger)Each subsidiary is wholly-owned.