Conservation initiatives on working ranches balance flexibility for land management with restrictions to ensure protection over time. Conservation easements are a common tool for range conservation, but the perpetual nature of their individually negotiated rights and restrictions may present a challenge for adaptive land management. The evolution of conservation easement approaches to land management was addressed in a review of 52 grazing easements created by The Nature Conservancy (TNC) in California rangelands between 1973 and 2006 as well as through interviews with TNC staff. Easement terms related to land management increased in complexity over time, particularly for purchased easements on private land. Easements commonly contained restrictions on riparian or wetland management (58%), residual dry matter (50%), and type of animal permitted (46%) but rarely restricted number of cattle or animal unit months (4%). Flexibility was provided by easement terms such as exceptions for drought years and reference to best management practices, the easement holder's administrative discretion, and easement amendment. Interviews with TNC staff revealed an iterative process in which conservation easements remain relatively fixed once they are established, whereas subsequent easements incorporate lessons learned from easement monitoring, enforcement, management, and applicable science. Conservation easements with an adaptive approach would link compliance terms with conservation goals, require monitoring of those terms, and have a mechanism for altering land management based on monitoring results. All three of these realms present challenges for the conservation easement structure. Improvements could be made in easement terms, ecological monitoring, and stewardship to improve the effectiveness and adaptability of this tool for maintaining ecological function on working ranches.