The commercial harvest of forest mosses and liverworts is an international, multimillion dollar industry with a potential ecological impact extending beyond the degradation of the slow-growing moss communities themselves. It is therefore important to develop guidelines for sustainable harvest, which may be preferable to complete prohibition. We present here guidelines (originally developed for the International Association of Bryologists) for policy makers, land managers, and harvesters based on moss harvest studies and input from bryologists, ecologists, nontimber forest product specialists, land managers, and commercial moss harvesters and buyers. Policy guidelines include standardizing reporting requirements, requiring the tumbling of moss before export, and creating incentives for buyer and harvester participation. Management guidelines include promoting salvage harvest, conducting inventories, and developing harvest guidelines in cooperation with local harvesters. Harvest guidelines, which must be region-specific, should cover the where, what, and how of sustainable harvest.