ASA as an abbreviation or initialism may refer to:

• Acoustical Society of America
• Advertising Standards Authority (disambiguation)
• African Studies Association
• Aid to Southeast Asia, a non-governmental organization
• Airline Superintendents Association of Trinidad & Tobago
• Air Services Australia, air traffic management and related services provider for Australia
• Albany Students' Association, at Massey University's Albany Campus in Auckland, New Zealand
• Alpha Sigma Alpha (ΑΣΑ), U.S. national sorority
• Amateur Softball Association, national governing body of Softball
• Amateur Swimming Association, UK governing body for swimming
• American Sailing Association
• American Scientific Affiliation, an organization of Christians in science
• American Seniors Association
• American Society for Aesthetics
• American Society of Agronomy
• American Society of Anesthesiologists
• American Society of Appraisers
• American Sociological Association
• American Sportscasters Association
• American Staffing Association
• American Standards Association, name of the American National Standards Institute from 1928 to 1966
• American Statistical Association
• American Student Assistance
• American Studies Association
• American Stroke Association, or American Heart Association
• American Sunbathing Association, former name of the American Association for Nude Recreation
• American Synesthesia Association
• Americans for Safe Access, marijuana law reform group
• Associate of the Society of Actuaries
• Association of Social Anthropologists
• Association of Southeast Asia
• Astronomical Society of Australia, the professional society of astronomers in Australia
• Australian Society of Authors, the peak professional association for Australian literary creators
• Austrian Service Abroad, provider of alternative Austrian national service
• Austrian Space Agency
• Austrian Studies Association  
• Autism Society of America
• United States Army Security Agency, the U.S. Army's electronic intelligence arm

Asa may refer to:
In people:

• Asa (name), a given name (including a list of persons with the name)
• Asa people, an ethnic group of Tanzania
• Asa language, of the Asa people
• Asa, god of the Kamba people ethnic group in Kenya
• Aṣa, a Nigerian French singer-songwriter and recording artist
• Asa of Judah, a king of Judah according to the Bible
• Asa (rapper), a Finnish rapper

Åsa [pronounced aw-suh] is a female first name in Sweden and Norway. Among the bearers are:

• Åsa Domeij, former politician for the Swedish Green Party
• Åsa Larsson, Swedish crime-writer
• Åsa Svensson, Swedish tennis player

Alpha Sigma Alpha (ΑΣΑ) is a United States National Panhellenic sorority founded on November 15, 1901 at the Virginia State Female Normal School (later known as Longwood College and now known as Longwood University) in Farmville, Virginia. The purpose of the association is to cultivate the relationship among members. Alpha Sigma Alpha promotes high ideal and standards for its members throughout their lives by emphasizing balance among four aims of intellectual, physical, social and spiritual development. With the effort of each member, Alpha Sigma Alpha became a full member of National Panhellenic Conference in 1951. The insignia of Alpha Sigma Alpha are the star, crown, palm tree and phoenix. The star represents the aspirations of Alpha Sigma Alphas to live up to the values of the Sorority. The crown represents leadership attained and the name of recognition given to our alumnae. The palm tree represents an emblem of sturdy development. The phoenix, the central symbol in our coat-of-arms, openly represents the reorganization of the Sorority that occurred in 1914. There are currently over 175 chapters of Alpha Sigma Alpha nationwide with more than 120,000 members.

In Old Norse, (or , plural ; feminine , plural ) is the term denoting a member of the principal pantheon in the indigenous Germanic religion known as Norse religion. This pantheon includes Odin, Frigg, Thor, Baldr and Týr. The second pantheon comprises the Vanir. In Norse mythology, the two pantheons wage the Æsir-Vanir War, which results in a unified pantheon.