Institutions striving to conserve biological diversity spend millions of dollars on initiatives worldwide but rarely define, measure, and communicate conservation success. Conservation funding is finite and needs to be allocated optimally. To achieve this, two important issues require attention. First, we need more systematic evaluation of the impacts and costs of individual approaches and more synthesis of site-specific information to enable comparisons of relative effectiveness among conservation approaches. Second, there must be stronger links between site-specific initiatives and global monitoring of biodiversity. The information used by institutions to monitor the status of biodiversity at all scales rarely connects with the institutions attempting to conserve biodiversity. In the last 15 years there has been an increase in the assessment of outcomes from, not just inputs to, conservation projects. But the recent financial constraints of governments and nongovernmental organizations (NGOs) and foundations have, ironically, resulted in decreased monitoring just when we need it most if we are to invest limited resources wisely. Strong monitoring programs have contributed to conservation successes in several cases. For example, some whale species may have benefited from policies reinforced by international and national monitoring efforts. Although these efforts were too late to avoid the disappearance of the Atlantic populations of gray whales (Eschrichtius robustus), the western Pacific populations have been increasing over many years. This success story helps demonstrate the potential conservation value of marine protected areas and whaling regulation. Also, Costa Rica’s recent national commitment to conservation and biodiversity monitoring in its development policies has resulted in designation of 25% of that nation as protected habitat. Although much of the country has been deforested, serious protection and monitoring of remaining habitat has sustained the ecological tourism that helps support conservation. However, there are too many counterexamples. There were an estimated 1000 giant pandas (Ailuropoda melanoleuca) remaining in the wild in the 1980s; and current estimates indicate there may now be only about 600. The conservation community is still struggling to measure the actual number of pandas remaining. Estimates of those numbers and descriptions of the methods to obtain them are surprisingly hard to find in the peer-reviewed or other literature. Without them, how can we agree on the best methods for panda conservation? The same challenges remain for monitoring and conserving habitats. Government officials, conservation organizations, private corporations, and others all ask how to spend their dollars most effectively. How does the governor seeking to conserve a state’s ecosystems, or an NGO seeking to conserve an ecoregion, decide which conservation approach or set of approaches will be most effective? How does a nation that has ratified the International Convention on Biodiversity select interventions that will help demonstrate a decrease in the rate of loss of biodiversity? The answers depend on the specific conservation goals of the implementing institution and the particular features of the landscape. One cannot answer these questions without evaluating the effectiveness of conservation approaches from multiple disciplines and perspectives. We face the challenge of determining not only the effectiveness of any one approach to conservation, but also the relative effectiveness of different approaches. The causes of biodiversity loss are complex, and implementing effective conservation strategies is an enormous challenge. Biological diversity exists in a mixed landscape of public and private lands and is affected by a wide range of institutions and individuals interacting in complex ways with diverse motivations and values. Even the term biological diversity is defined and used differently in different projects. In most projects, either the conservation goal is never specified or it is confused with the conservation strategies being applied. For example, a project goal may be described as “obtaining a conservation easement” rather than using an easement as a tool to protect the species or habitat. An evaluation of 210 biodiversity projects funded through the Global Environment Facility found that only 17 had sufficient information to assess the impact of the project on biodiversity (Singh & Volonte 2001). Most evaluations of conservation projects have been more anecdotal than empirical and have tended to measure effectiveness narrowly. A project aimed at increasing