PDA may refer to:

• Parts departing aircraft, mid-air loss of screws, rivets, doors, etc.
• Patron-driven acquisition, a mechanism for libraries to purchase books
• Personal digital assistant, an early kind of mobile device
• Photodiode array, a type of detector
• Pitch detection algorithm, to find the pitch of a signal
• Polydiacetylenes, a family of conducting polymers
• Predictive analytics, a form of business analytics
• Pushdown automaton, in automata theory

• Pancreatic ductal adenocarcinoma, the main type of pancreatic cancer
• Pathological demand avoidance, in psychology
• Patent ductus arteriosus, a heart defect
• Posterior descending artery, an artery
• Potato dextrose agar, a microbiological media for culturing yeast and fungus

• "PDA" (Interpol song), a song by Interpol
• "PDA", a song by the Backstreet Boys from This Is Us
• "PDA", a song by Audio Adrenaline from Audio Adrenaline
• "P.D.A. (We Just Don't Care)", a song by John Legend

• Parenteral Drug Association, a global pharmaceutical trade association
• Pharmacists' Defence Association, UK
• Peruvian Debate Association, for inter-school debating
• Pinoy Dream Academy, the Philippine franchise of Endemol's Star Academy
• Population and Community Development Association, Thailand
• Private defense agency, an enterprise which would provide personal protection and military defense services to individuals
• Professional Driver Association, of NASCAR drivers before the 1969 Talladega 500
• Public development authority, government-owned corporations in Washington, US

• Alternative Democratic Pole, a political party in Colombia (Polo Democrático Alternativo)
• Progressive Democratic Alliance, a former political party in British Columbia, Canada
• Progressive Democrats of America, a progressive political organization
• Party of Democratic Action, a Bosniak party in Bosnia-Herzegovina
• Movement of Democratic Action, a political party in Bosnia-Herzegovina (Pokret demokratske akcije)
• Aruban Democratic Party, an Aruban political party (Partido Democrático Arubano)

• Public display of affection, an act of physical intimacy in the view of others
• Pregnancy Discrimination Act, US
• "PDA" (The Office), an episode from the American television sitcom The Office
• Past Doctor Adventures, spin-off novels from the BBC's Doctor Who
• Pub Design Awards, UK
• Professional Development Award, offered by the Scottish Qualification Authority