Jose' Luis Sert, who died Tuesday at age 80 in his native Barcelona, was a creator of unusual dimension, an architect, planner and educator whose influence in each field was extensive.

It was the range of his skills and intellectual interests, rather than triumphant accomplishment in a single area, that accounts for Sert's formidable stature in the world of 20th-century design.

He was a leader of the International Congresses for Modern Architecture, those historic gatherings of the architectural avant-garde in the 1920s and 1930s that did much to set planning agendas for the post-World War II world. He was dean of the Graduate School of Design at Harvard University for 16 years, from 1953 to 1969. And throughout his adult life he was an architect with impressive buildings in the United States and abroad.

Sert can be characterized accurately as a "second-generation modernist"--his early work with Le Corbusier in Paris in the late 1920s had a lasting effect--but the phrase encompasses neither his growth nor the strong, subtle spirit that informed his human ties and the best of his works.

Peter Blake, chairman of the architecture department at Catholic University, who first encountered Sert when Sert was a practicing architect in New York City in the late 1940s, warmly recalls that "despite the fact that he Sert was very small--absolutely tiny--he was a very towering figure."

Dorn McGrath, chairman of the department of urban and regional planning at George Washington University and a student at the Graduate School of Design when Sert was its dean, tersely sums up his impressions of Sert: "He was a great gentleman and a staunch Catalan who left us all with a whole lot to think about."

Robert Campbell, the architecture critic of the Boston Globe, who worked with the architectural firm of Sert, Jackson and Associates from 1968 to 1975, observes that Sert "was a very complex guy, very ambitious as an architect," who "was always trying to solve larger problems than the program seemed to present."

The interrelated themes of art, architecture and planning run through Sert's personal and professional life. Born in 1902 to an aristocratic, artistic Catalan family, Sert began his career as a painter before switching to architecture in the mid-1920s. But he never lost his love for painting and sculpture.

Miro', Picasso and Calder became his great friends. He designed a stunning studio for Miro' on Majorca in 1955 and, later, a beautifully textured and light-filled museum for the Maeght Foundation in Saint-Paul-de-Vence, France, with its entrancing "Miro' Labyrinth." And it was Sert, as designer of the Spanish pavilion for the 1938 World's Fair in Paris, who gave Picasso the commission that resulted in "Guernica," the searing indictment of fascism and war that returned just two years ago to Spain.

Sert maintained throughout his life his commitment to social justice. As the leader of the Spanish architectural avant-garde and close ally of the Spanish Republic he was a signer, 50 years ago, of the Charter of Athens, the first comprehensive statement of modernist ideals and practices in the domain of urban design and planning.

In his 1942 book, "Can Our Cities Survive?" Sert systematically expanded upon the principles in this short document. Later in his life, Sert, like many others, became disenchanted with the limitations of large-scale, sweep-the-slate-clean modernist planning. He was, for instance, a strong supporter of the Charter of Machu Picchu, the 1977 revision of the Charter of Athens.

But if the early modernist planners and architects left us with a vast unfinished program, their very attempt to grapple with the complexity of worldwide urban problems was in itself a significant achievement. Dorn McGrath is certainly correct when he points out that in their holistic approach "Sert and his colleagues really established the foundation for the essential principles of city planning and their integration with architecture."

These principles were important in Sert's long tenure as dean of Harvard's Graduate School of Design and also in Sert's architectural practice. Sert was one of the many great creative e'migre's who enriched American cultural life during World War II and after. He came to New York in 1939, establishing (with Paul Lester Weiner and Paul Schulz) the firm of Town Planning Associates, which in its 18-year existence developed plans and housing projects for many Latin American cities and towns. In 1958 he opened the architectural office in Boston.

Sert's major building projects in this country include a large community and housing complex on Roosevelt Island in New York and numerous buildings in Boston and Cambridge. The best known of these are the Married Student Dormitories he designed for a site along the Charles River and the Holyoke Center, a combined health center, office building and retail complex near Harvard Square.

It is possible to be of two minds about these buildings. They are praiseworthy in their logic and complexity. Even the busyness of their fac,ades, with their contrapuntal, rectilinear rhythms of colors and textures, adds a welcome richness to the modernist lexicon. So as modern buildings they are way above average. But they do stick out so, like outposts having little to do with the history and light of New England.

The same, of course, could be said of Le Corbusier's Carpenter Center at Harvard, a sculptural concrete building that is so broodingly different from the airy rationalism of Sert's Harvard structures. This bears mentioning because the building is the only one Le Corbusier fully designed in this country, and it was Sert, as dean, who persuaded the university to make the commission.

Sigfried Giedion, the historian of the modernist movement and Sert's friend, once wrote that Sert "maintains a Catalan atmosphere around him." Sert and his wife, Moncha, entertained generations of architects and students in their Cambridge home, a place of patios and simple elegance, like a transplanted piece of Mediterranean culture.

It is therefore not surprising that Sert's very best architectural works were made for the Mediterranean environment--in southern France, Majorca and the smaller Balearic island of Ibiza. In these places Sert's knowledge of the landscape, the light, the people and the long tradition of folk architecture paid rich aesthetic dividends in buildings that speak at once to the present and to the past.