In 1943 MacCready graduated from Hopkins School in New Haven. In 1947 he received his Bachelor of Science in physics from Yale University. His interest in flight grew to include gliders. He won the 1948, 1949 and 1953 U.S. National Soaring Championships, pioneered high-altitude wave soaring in the United States; and in 1947 was the first American in 14 years to establish an international soaring record. (The 1999 National Soaring Convention of the Soaring Society of America was dedicated to him.) He represented the United States at contests in Europe four times, becoming International Champion in France in 1956, the first American to achieve this goal.

During the decade 1946-56, MacCready worked on sailplane development, soaring techniques, meteorology, and invented the Speed Ring Airspeed Selector that is used by glider pilots worldwide to select the optimum flight speed between thermals (commonly called the "MacCready Speed"). Concurrently, he earned a master's degree in physics in 1948 and a Ph.D. in aeronautics in 1952 from the California Institute of Technology, and in 1950-51 managed a weather modification program in Arizona. He founded Meteorology Research Inc., which became a leading firm in weather modification and atmospheric science research. He pioneered the use of small-instrumented aircraft to study storm interiors and performed many of the piloting duties.

In 1971, MacCready started AeroVironment, Inc., a diversified company headquartered in Monrovia, California. Products include environmental instrumentation, surveillance aircraft, and power electronic systems for stationary and mobile uses. MacCready is Chairman of the Board of AeroVironment, and active in all the technology areas.

MacCready became internationally known in 1977 as the "father of human-powered flight" when his Gossamer Condor made the first sustained, controlled flight by a heavier-than-air craft powered solely by its pilot's muscles. For the feat he received the $95,000 Henry Kremer Prize. Two years later, his team created the Gossamer Albatross, another 70-pound craft with a 96-foot wingspan that, with DuPont sponsorship, achieved a human-powered flight across the English Channel. That flight, made by "pilot-engine" Bryan Allen, took almost three hours. It won the new Kremer prize of $213,000, at the time the largest cash prize in aviation history.

Subsequently, the AeroVironment team led by MacCready developed, under DuPont sponsorship, two more aircraft, this time powered by the sun. In 1980, the Gossamer Penguin made the first climbing flight powered solely by sunbeams. In 1981, the rugged Solar Challenger was piloted 163 miles from Paris, France to England, at an altitude of 11,000 feet. These solar-powered aircraft were built and flown to draw world attention to photovoltaic cells as a renewable and non-polluting energy source for home and industry and to demonstrate the use of DuPont's advanced materials for lightweight structures.

In 1983, his team built the 70-pound, human-powered (with on-board battery energy storage) Bionic Bat, partly to vie for new Kremer speed prizes and partly to explore new technologies leading toward practical, long-duration, unmanned vehicles and quiet, slow-speed, piloted aircraft. In 1984, the Bionic Bat won two of the speed prizes.

Starting in 1984, the team developed a large radio-controlled, wing-flapping, flying replica of the largest animal that ever flew: the long-extinct pterodactyl Quetzalcoatlus northropi, whose giant wings spanned 36 feet. This QN replica became the lead "actor" in a 1986 wide-screen IMAX film titled "On the Wing", a film depicting the interrelation between the developments of biological flight and aircraft. Johnson Wax and the National Air and Space Museum sponsored the film and the QN replica.

Recent "cover story" type aircraft of his AeroVironment groups start with the 100-foot remotely piloted solar powered Pathfinder that, in 1997, reached the stratospheric altitude of 71,500'. In 1998, the 120 foot Pathfinder Plus reached over 80,000 feet (the highest any powered airplane has maintained level flight), and the 206 foot Centurion, designed for 100,000 feet, started low altitude tests. The Centurion then evolved into the 247-foot prototype Helios. This underwent low altitude tests in 1999 as a step toward "near-eternal" (6 month) flights when the solar cells and the regenerative fuel cell system power the final Helios. These NASA-supported developments are steps toward non-polluting flights in the stratosphere for environmental studies and surveillance. The largest potential is for Helios to serve as an 11-mile-high "SkyTower"™ that relays multichannel wide bandwidth communications. Other widely publicized pioneering aircraft are at the other end of the size range: tiny (6" span) surveillance drones, microplanes with on-board video cameras, featuring gross weight under 2 ounces.

His team's first land vehicle was the GM Sunraycer, for which AeroVironment provided project management, systems engineering, aerodynamics and structural design, power electronics development, as well as construction and testing for General Motors and Hughes Aircraft. In November 1987, this solar-powered car won the 1,867-mile race across Australia, averaging 41.6 mph (50 percent faster than the second place vehicle in the field of 24 contestants). The goal of the Sunraycer, in addition to winning the race, was to advance transportation technology that makes fewer demands on the earth's resources and environment, and to inspire students to become engineers. AeroVironment also helped with the GM-sponsored educational tour of the Sunraycer, spearheaded a course at Caltech on the Sunraycer engineering design (course notes were distributed in book form by SAE), and helped manage, for GM, the Sunrayce, in which solar-powered cars from 32 university groups raced from Florida to Michigan in July 1990. In January 1990, the GM Impact was introduced, a battery-powered sports car with snappy "0 to 60 mph in 8 seconds" performance. GM later turned the Impact into the production vehicle EV-1. The AV team provided the initial concept for the Impact; performed program management, systems engineering, and design of the electrical and mechanical elements; and built the vehicle, integrating the participation of a dozen GM divisions. This pioneering car became a catalyst for the present intense global developments of battery-powered and alternatively-fueled vehicles.

The unique vehicles produced by MacCready's teams have received international attention through exhibits, books, television documentaries, and innumerable articles and cover stories in magazines and newspapers. They, MacCready, and AeroVironment have become symbols for creativity. The Gossamer Condor is on permanent display at the Smithsonian's National Air and Space Museum in Washington, D.C., adjacent to the Wright Brothers' 1903 airplane and Lindbergh's Spirit of St. Louis. A film about it, "The Flight of the Gossamer Condor", won the Academy Award for Best Documentary - Short Subject in 1978. The Gossamer Albatross, after touring U.S. science museums, was for some years hung in the central atrium of the London Science Museum. Now in storage, it is slated for a forthcoming NASM facility at Dulles. The almost-identical backup vehicle, Gossamer Albatross II, was flown in the Houston Astrodome, and on a NASA research project. It now hangs at the Museum of Flight in Seattle. The Gossamer Penguin was exhibited in the U.S. Pavilion of the 1982 World's Fair in Knoxville, Tennessee. The Solar Challenger was displayed at the National Air and Space Museum, and at Expo '86, and is now at the Science Museum of Virginia in Richmond. The QN flight replica, after being on display at the National Air and Space Museum in conjunction with showing the "On the Wing" film, now rests at the Smithsonian Zoo. A full size static display version is at the Museum of Flying at Santa Monica airport. The Sunraycer is stored at the Smithsonian American History Museum, and is displayed occasionally.

MacCready's achievements have brought him many recent honors, including:

Distinguished Alumni Award, 1978, California Institute of Technology

Collier Trophy, 1979, by the National Aeronautics Association ("awarded annually for the greatest achievement in Aeronautics and Astronautics in America"

Reed Aeronautical Award, 1979, by the American Institute of Aeronautics and Astronautics ("the most notable achievement in the field of aeronautical science and engineering"

Edward Longstreth Medal, 1979, by the Franklin Institute

Ingenieur of the Century Gold Medal, 1980, by the American Society of Mechanical Engineers; also the Spirit of St. Louis Medal, 1980

Inventor of the Year Award, 1981, by the Association for the Advancement of Invention and Innovation

Klemperer Award, 1981, OSTIV, Paderborn, Germany

I.B. Laskowitz Award, 1981, New York Academy of Science

The Lindbergh Award, 1982, by the Lindbergh Foundation ("to a person who contributes significantly to achieving a balance between technology and the environment")

Golden Plate Award, 1982, American Academy of Achievement

Gold Air Medal, by the Federation Aeronautique Internationale

Distinguished Service Award, Federal Aviation Administration

Public Service Grand Achievement Award, NASA

Frontiers of Science and Technology Award, 1986, first award in this category given by the Committee for the Scientific Investigation of Claims of the Paranormal

The "Lipper Award", 1986, for outstanding contribution to creativity, by the O-M Association (Odyssey of the Mind)

Guggenheim Medal, 1987, jointly by the American Institute of Aeronautics and Astronautics, the Society of Automotive Engineers, and the American Society of Mechanical Engineers

National Air and Space Museum Trophy for Current Achievement, 1988

Enshrinement in The National Aviation Hall of Fame, July 1991, Dayton, Ohio

SAE Edward N. Cole Award for Automotive Engineering Innovation, September 1991

Scientist of the Year, 1992 ARCS (Achievement Rewards for College Scientists), San Diego Chapter

Pioneer of Invention, 1992, United Inventors Association

Chrysler Award for Innovation in Design, 1993

Honorary Member designation, American Meteorological Society, 1995

American Society of Mechanical Engineers, Ralph Coats Roe Medal, November 1998

Howard Hughes Memorial Award, Aero Club of Southern California, January 1999

Calstart’s 1998 Blue Sky Merit Award, February 1999

1999 National Convention of the Soaring Society of America, dedicated to Paul MacCready, Feb. 1999

Special Achievement Award, Design News, March 1999

Included in Time magazine’s "The Century’s Greatest Minds" (March 29, 1999) series "on the 100 most influential people of the century"

Lifetime Achievement Aviation Week Laureate Award, April 1999

Commemorated in Palau stamp, 1 of 16 "Environmental Heroes of the 20th Century", Jan. 2000

Institute for the Advancement of Engineering William B. Johnson Memorial Award, Feb. 2000

In 1999, MacCready directed prize money from the Design News Special Achievement Award to Harvey Mudd College, initiating an industry/student development of a two-legged walking robot.

MacCready has many professional affiliations, including the National Academy of Engineering and the American Academy of Arts and Sciences, and Fellow status in the American Institute of Aeronautics and Astronautics, the American Meteorological Society (he is also an AMS Certified Consulting Meteorologist and a member of the AMS Council), and the Committee for the Scientific Investigation of Claims of the Paranormal. He is a Humanist Laureate of the Academy of Humanism. For two decades he has been International President of the International Human-Powered Vehicle Association; and in 1999 helped create the Dempsey-MacCready One Hour Distance Prize He has served on many technical advisory committees and Boards of Directors for government, industry (public and private corporations), educational institutions, and foundations; and is at present a Director of the Lindbergh Foundation and the Society for Amateur Scientists. He has a dozen patents.

He has been awarded five honorary degrees (including Yale 1983) and made numerous commencement addresses. He has written many popular articles, and authored or co-authored over one hundred formal papers and reports in the fields of aeronautics; soaring and ultralight aircraft; biological flight; drag reduction; surface transportation; wind energy; weather modification; cloud physics; turbulence, diffusion, and wakes; equipment and measurement techniques; and perspectives on technology, efficiency, and global consequences and opportunities. He lectures widely for industry and educational institutions, emphasizing creativity and the development of broad thinking skills, and also treating issues such as future paths for energy and transportation, and the changing relationship between nature and technology.

MacCready lives in Pasadena, California, with his wife Judy. Their three sons, all of whom were involved in the early human- and solar-powered aircraft developments, are now following their independent career paths.