DUKE Ellington was born in Washington in 1899, grew up at 1212 T St. NW and, after dropping out of Armstrong High School several months before graduation, was booking his first band into local dance halls for $5 a night. When he died in 1974 he was recognized worldwide as a major 20th-century composer, a preeminent orchestra leader and one of the most influential jazz musicians.

Thursday through Sunday, the local chapter of the international Duke Ellington Society will host a conference whose stated purpose is to foster "appreciation and understanding of Ellington's music and to learn what books and publications are available and what we can all do to keep Ellington and his music alive for generations to come." Scholars and collectors from this country and abroad will present papers and participate in panel discussions, rare film footage of the great orchestra will be shown, and several Ellington band alumni will attend. A concert of Ellington's music by the Army Blues will kick off the four-day meeting Thursday evening in Brucker Hall, Fort Meyer, and a sightseeing bus tour of Ellington landmarks will conclude the conference Sunday. (Headquarters will be at the Hampshire Motor Inn, Langley Park, but locations of the various functions will be scattered. For more information call 559-4126.)

Terrell Allen, president of the Washington chapter since the early 1960s, reminisced about his introduction to Ellington's music and to the Duke himself: "I first heard the Ellington band on record back in 1934 when I was a young buck," he said, recalling his early years in Pittsburgh. "I come from a very orthodox religious family and they thought all that kind of music was the devil's music, and I had to sneak out when I was 11 or 12 to go hear jazz." Allen had already caught the band at the Apollo Theatre in New York before his family moved to Washington in 1939 and he began to regularly attend band performances at the Howard theater. He remembers Ellington as "very, very gracious to teen-agers, he never fluffed us off. Very regal, but not an aloof person. And every opportunity I had I'd go backstage and speak to him. I called him Mr. Ellington and when I got older I called him Duke."

Longtime Ellington Society member Jack Towers describes the organization as "a device to get a bunch of folks together of like mind to re-examine and keep abreast of what turns up in the way of Duke's stuff." Towers says that until a few years ago he assumed the well had run dry, but that broadcasts recorded at home as early as the 1930s and "shellac pressings of takes that had never appeared before" are now surfacing at such a rate they constitute "an avalanche."

Besides open meetings on the first Saturday evening of every month at the Omega Psi Phi house on the campus of Howard University, the local chapter of the Duke Ellington Society maintains an informal correspondence with chapters in New York, Chicago and Toronto, and with individual members throughout the world. Last week it initiated a projected ongoing relationship with the Ellington School of the Arts with a film-lecture that it expects to repeat annually. Not least among the society's objectives is to encourage area broadcasters to air more of Ellington's music. And until Ellington's death, whenever his orchestra was in the area, it was always entertained at the fraternity house or at the home of a society member. The Duke sometimes was not able to attend, but when he could make it, says Allen, "it was very special."

Among the participants in the conference will be several eminent Ellington researchers from abroad including jazz film scholar Klaus Stratemann from Germany, Eddie Lambert from England and Joe Hoefsmit from The Netherlands.

The Smithsonian's Martin Williams will speak on Ellington as a composer and Dan Morgenstern of Rutgers' Institute of Jazz Studies will discuss "Duke and the Tiger Rag." A longtime associate of Ellington, Pat Willard, will come from California to offer some personal insight on the band leader's last and uncompleted project, the musical "Queenie Pie." Friday night will feature "A King's Ransom of Ellington's Cinematic Features and Featurettes," presented by a chief collector of Ellingtoniana, Jerry Valburn. And somewhere in the crowded schedule a place will be found for Washington guitarist Bill Harris to play a medley of Ellington compositions.

The frosting on the cake will be the opportunity for guests to rub shoulders with some Ellington alumni, including several who reside in the area: saxophonist and band leader Rick Henderson, vocalist Jimmy McPhail and, hopefully, bassist Billy Taylor. Former Ellington band vocalist June Norton and clarinetist Barney Bigard's widow are also expected. Dennette Harrod, who has had a lifetime love affair with the Ellington orchestra since he first met its leader at the stage door of the Howard theater in September of 1931, will host a reunion reception with these surviving associates of the Duke. Harrod will also play a tape of a recent telephone interview he conducted with trombonist Lawrence Brown (now living in California), whose membership in the Ellington Orchestra began in 1931 and ended in 1970.