Diplomats from Washington's 168 embassies and legations do more than write treaties, arrange ceremonial visits by heads of state and negotiate trade agreements. Many, particularly those from the more affluent countries with their talented press and information officers, make efforts to become at least temporary citizens of the capital by joining in local events and helping to meet local needs.

One of the most adept at making friends for his country while helping local charities was Martin Eichtinger, who headed the Austrian Press and Information Service here for 7 1/2 years. Last month he returned to Vienna to be the Austrian Industry Federation's foreign affairs adviser.

Eichtinger promoted--some say instigated--the popular Vienna waltz balls here. Modeled after the traditional Viennese event, the Washington version benefits SOS Children's Villages-USA. The parent organization is a private, nonprofit group founded in Austria.

Eichtinger once admitted with some embarrassment that he had danced at many of the 250 yearly balls in Vienna but never at the Viennese Opera waltz balls so popular there since the first one, held on Dec. 11, 1877. To encourage ballgoers here, he held waltz classes at the embassy.

The two Washington balls raised $140,000 to help finance a feasibility study headed by Colin Powell to build a Children's Village in the District. "For 50 years, Children's Villages has successfully provided safe homes for abused and neglected children around the world in 371 villages in 128 countries," Eichtinger said.

Eichtinger also endeared himself to artists and art lovers by arranging exhibits of paintings--some by Austrians and some by local artists--to embellish the embassy's great hall, which can seat 450 guests.

By no means are the Austrians the only ones who practice diplomacy by sponsoring local charities and cultural events.

To celebrate the 50th anniversary of the founding of the People's Republic of China, Ambassador and Mrs. Li Zhaoxing gave a bountiful reception earlier this month. Magnificent Chinese light shades and Chinese art offered visual delights to complement the supper of edible delights, including a rice dish the Chronicler had never tasted before. The buffet reception was planned as a prelude to encourage the diners to go on to the Washington Symphony Orchestra concert at Constitution Hall, with ticket proceeds going to the orchestra.

Next week, Finnish Ambassador Jaakko Laajava and his wife will be the hosts for an evening to benefit the Young Concert Artists of Washington. Finnish cellist Jan-Erik Gustafsson, Russian violist Anton Barachovsky and American pianist Wendy Chen will perform an international concert at the embassy, followed by a buffet dinner and live auction of gifts from the embassies.

Also sponsoring the event are French Ambassador and Mrs. Bujon de l'Estang, Turkish Ambassador and Mrs. Baki Ilkin, German Ambassador Juergen Chrobog and Magda Gohar-Chrobog and Russian Federation Ambassador Yuri Viktorovich Ushakov, with co-chairmen Gilan Tocco Corn and Aniko Gaal Schott.

Belgian Ambassador Alex Reyn and his wife will give the Armistice Day fall benefit for Woodrow Wilson House at their Foxhall Road residence on Nov. 11. This year is the 80th anniversary of Wilson's visit with Belgium's King Albert, when the president was trying to inaugurate the League of Nations. The Wilson Statesmanship Award will be presented that night to U.N. Secretary-General Kofi Annan "in recognition of the leadership . . . that he has brought to the United Nations, the successor to Wilson's League of Nations."

The famous Meridian House annual ball was held this past Friday. Before the dancing began, 25 embassies gave dinners for 30 guests each.

Embassies also often donate food and wine to charitable auctions. But the most popular items to offer up for bid, the German Embassy's Christa Bluehdorn said, are international flights with free hotel reservations abroad. Unfortunately, she added, "it is harder now to get the airlines to donate them."

The Adopt an Embassy program for sixth-grade District students is one of the most successful efforts. Bluehdorn says some 50 embassies participate. "Embassy wives and others go to the schools to talk about their countries, and sometimes invite them to visit the embassies," she said.

And tomorrow's mail will doubtless bring still more invitations from Washington's other gifted practitioners of party diplomacy.

CAPTION: The Viennese Opera Ball benefiting SOS Children's Villages-USA is an elegant event on Washington's social calendar.