Rigorously designed experiments and the primary data that they generate are powerful tools in ecology that define and shape ecological theory. However, many problems and questions require that the results of individual experiments or studies be brought together in a synthetic way. Such scientific synthesis can enable ecological understanding within a larger context by comparing results from different species, time scales, or ecosystems. Specialized kinds of synthesis can also create new insights about central tendency, strength of association, and certainty/uncertainty that integrate findings across a variety of study types, species, and systems. The very successful work of synthesis centers in the U.S. (e.g., National Center for Ecological Analysis and Synthesis, National Socio-Environmental Synthesis Center, Powell Center) and others around the world showcase the value and application of scientific synthesis, and ecological synthesis, in particular. One important application of scientific synthesis is evidence-based environmental decision-making. The process of decision-making often relies on analysis and interpretation of secondary data and information (i.e., data and information used by someone besides the individual that originally generated and analyzed it). The scale of the decision (geographic, political, cost) often dictates the scale of the relevant supporting data – which can be quite large. The challenges associated with secondary data acquisition, analysis, and communication are probably familiar to those who have conducted quantitative meta-analysis. They also exist for other forms of qualitative synthesis like conceptual syntheses, causal analysis, and risk assessment. In this session, we introduce how ecologists are connecting secondary data synthesis to environmental decision-making. We lay bare the challenges that exist for scientists utilizing secondary data to inform decisions in different scales and contexts with various requirements for specificity, comprehensiveness, timeliness, rigor and transparency. We will explore state-of-the-art methodologies for secondary data analysis and interpretation that cut across several fields of environmental decision-making, including application to national-scale US environmental policy and international environmental management. We will address translational aspects of communicating results from scientific synthesis. Finally, we will look ahead to the next generation of bringing together secondary data and why ecologists should lead the way. Note: This session was submitted and accepted for the 2020 annual meeting but was withdrawn in deference to pandemic challenges faced by several presenters. In this re-submission, we have updated the description to align more closely to the theme of the 2021 annual meeting.