Context A framework was developed to help investors improve the delivery of environmental benefits from environmental programs. The framework, Investment Framework for Environmental Resources (INFFER), assists environmental managers to design projects, select delivery mechanisms and rank competing projects on the basis of benefits and costs. Aims To identify design requirements for an environmental investment framework on the basis of consideration of lessons from practical experience, and established theory from decision analysis and economics. Methods The design and delivery of the framework are based on extensive experience from working with environmental managers and policy makers. In addition, the developers have paid close attention to the need for processes that are theoretically rigorous, resulting in a tool that allows valid comparison of projects for different asset types, of different scales and durations. Key results From the practical experience outlined, several important lessons and implications are identified, including the need for simplicity, training and support of users, trusting relationships with users, transparency, flexibility, compatibility with the needs and contexts of users, and supportive institutional arrangements. Use of a theoretically correct metric to rank projects can deliver dramatically improved environmental values relative to a commonly used weighted additive metric. Conclusions Practical and theoretical considerations have strong implications for the design of a practical, effective and accurate tool to support decision making about environmental project priorities. © 2013 CSIRO.