Long-term, place-based research programs in the National Science Foundation-supported Long Term Ecological Research (LTER) Network have had profound effects on public policies and practices in land use, conservation, and the environment. While less well known than their contributions to fundamental ecological science, LTER programs’ commitment to serving broad public interests has been key to helping achieve their mission to advance basic science that supports society’s need to address major environmental challenges. Several attributes of all LTER programs are critical to these accomplishments: highly credible science, strong site-level leadership, long-term environmental measurements of ecosystem attributes that are relevant to the public and to resource managers, and effective and accessible information that supports sound management practices. Less recognized attributes of three case study LTER sites (Andrews Forest, Harvard Forest, Hubbard Brook) which have contributed to major impacts include strong interdisciplinary research communities with cultures of openness, dispersed leadership within those communities, a commitment to carry science perspectives to society through multiple governance processes, strong public-private partnerships, and communications programs that facilitate the exchange of information and perspectives among science communities, policy-makers, land managers, and the public. Taken together, these attributes of sites drive on-the-ground outcomes. These case studies reveal a virtue of the long-term nature of LTER not anticipated when the program began: that the decades-long engagement of a place-based, science community can have a major impact on environmental policies and practices. These activities, and the cultivation of science communities that can accomplish them, go beyond the initial directives and review criteria for LTER site proposals and programs.