The Long Island Index receives data from a variety of governmental agencies and organizations.
Special thanks to the following groups for sharing their data and expertise:
| Center for Governmental Research Center for Urban Research | Central Pine Barrens Joint Planning & Policy Commission |
| CUNY Graduate Center | City of Glen Cove |
| Columbia University, Teachers College | City of Long Beach |
| Hofstra University | Long Island Bus |
| Long Island Pine Barrens Society | Long Island Real Estate Report |
| Metropolitan Transportation Authority—Long Island Rail Road | Nassau County Department of Public Works – Planning Division |
| Nassau BOCES | Nassau County Planning Department |
| New York State Department of Environmental Conservation, Region 1 | North Shore-Long Island Jewish Health System |
| New York State Department of Transportation | Regional Plan Association |
| PricewaterhouseCoopers / National Venture Capital Association MoneyTree™ Thomson Financial | Suffolk County Division of Planning & Environment |
| Stony Brook University, Center for Survey Research | New York State Education Department |
| Suffolk County Department of Social Services | Suffolk County Transit |
| Towns of Babylon | Town of Brookhaven |
| Town of East Hampton | Town of Hempstead |
| Town of Huntington | Town of Huntington HART Bus Systems |
| Town of Islip | Town of North Hempstead |
| Town of Oyster Bay | Town of Riverhead |
| Town of Shelter Island | Town of Smithtown |
| Town of Southampton | Town of Southold |
| Village of Babylon | Village of Farmingdale |
| Village of Freeport | Village of Greenport |
| Village of Hempstead | Village of Lynbrook |
| Village of Patchogue | Village of Port Jefferson |
| Village of Rockville Centre | Village of Valley Stream |
| Village of Westbury | |
| Center for Governmental Research Center for Urban Research | |
| Central Pine Barrens Joint Planning & Policy Commission | |
| CUNY Graduate Center | |
| City of Glen Cove | |
| Columbia University, Teachers College | |
| City of Long Beach | |
| Hofstra University | |
| Long Island Bus | |
| Long Island Pine Barrens Society | |
| Long Island Real Estate Report | |
| Metropolitan Transportation Authority—Long Island Rail Road | |
| Nassau County Department of Public Works – Planning Division | |
| Nassau BOCES | |
| Nassau County Planning Department | |
| New York State Department of Environmental Conservation, Region 1 | |
| North Shore-Long Island Jewish Health System | |
| New York State Department of Transportation | |
| Regional Plan Association | |
| PricewaterhouseCoopers / National Venture Capital Association MoneyTree™ Thomson Financial | |
| Suffolk County Division of Planning & Environment | |
| Stony Brook University, Center for Survey Research | |
| New York State Education Department | |
| Suffolk County Department of Social Services | |
| Suffolk County Transit | |
| Towns of Babylon | |
| Town of Brookhaven | |
| Town of East Hampton | |
| Town of Hempstead | |
| Town of Huntington | |
| Town of Huntington HART Bus Systems | |
| Town of Islip | |
| Town of North Hempstead | |
| Town of Oyster Bay | |
| Town of Riverhead | |
| Town of Shelter Island | |
| Town of Smithtown | |
| Town of Southampton | |
| Town of Southold | |
| Village of Babylon | |
| Village of Farmingdale | |
| Village of Freeport | |
| Village of Greenport | |
| Village of Hempstead | |
| Village of Lynbrook | |
| Village of Patchogue | |
| Village of Port Jefferson | |
| Village of Rockville Centre | |
| Village of Valley Stream | |
| Village of Westbury | |