In Defense of Animals, a non-profit organization for animal rights activism
Indian Dental Association
IDA Ireland, formerly the Industrial Development Authority
Infocomm Development Authority of Singapore, a statutory board of the Singapore government
Information Design Association
Ingeniørforeningen i Danmark or Danish Society of Engineers, an association for engineers and others in technology
Institute for Defense Analyses, a U.S. non-profit corporation that administers three federally funded research and development centers
International Dark-Sky Association, a U.S.-based non-profit organization
International Depositary Authority, established by the Budapest Treaty for the deposit the biological material for the recognition of patents, such as the Microbial Culture Collection
International Desalination Association, a global organization dedicated to desalination, desalination technology and water reuse
International Development Association of the World Bank Group
International Disability Alliance, an international alliance of individuals to defend the rights of those with disabilities
International Dispensary Association Foundation a NGO dedicated to improving access to medications in the developing world
International Documentary Association, a non-profit organization promoting documentary film, video and new media
International Dyslexia Association, a non-profit education and advocacy organization
Investment Dealers Association of Canada, now part of the Investment Industry Regulatory Organization of Canada
Issues Deliberation Australia/America, a public policy think tank based in South Australia and Texas
