Worldwide, more than 30,000 plant species are harvested from the wild by an estimated 3-5 billion people. These species play critical roles as foods and medicines, and in arts, rituals, and cultural identity. Overharvest has been documented as an important driver of population decline, yet many indigenous and local communities heavily harvest wild plant species while maintaining growing populations. We synthesize and analyze plant demographic and ethnobotanical studies of sustainable wild plant harvest to identify why and how heavily harvested populations can be maintained. Four stewardship practices emerge as commonalities across sustainable systems globally: harvest restrictions (including spatial, temporal, and size), enhancement of reproductive pathways, enhancement of habitat quality, and management of disturbance. Demographic studies demonstrate that these practices have a positive effect on population growth rates by altering rates of survival, growth and reproduction, and that this occurs via a wide range of ecological mechanisms. While indigenous and local stewardship of sustainably harvested species tends to involve multiple types of stewardship, local and global policies for sustainable use of wild plants focus exclusively on harvest restrictions. Conservation policies and practices that engage indigenous and local communities, and include stewardship practices that not only restrict, but that also build abundance, can more effectively ensure sustainable use.