President Pascal Couchepin has praised the Swiss abroad for acting as an "impressive body of potential ambassadors".
Addressing the contingent of about 670,000 expatriates for Switzerland's National Day on August 1, Couchepin said they brought know-how and knowledge to their new home countries.
"Switzerland needs friends to make its presence felt around the world and you are some of those friends. You embody the spirit of openness that has always served us well," he said.
Around a tenth of the Swiss population chooses to live outside the country, and last year record numbers - 120,000 - registered to vote in the federal elections after an appeal by the government.
Couchepin said this was testimony to their civic sense and ties to the country.
"The quality of those ties can be measured by your commitment to your homeland. That commitment is strong."
While most expatriates live in Europe, Asia was the fastest growing destination for Swiss in 2007.
Couchepin said all Swiss practised a sense of hospitality and were enriched by learning about and experiencing other cultures.
"We welcome many foreigners who contribute to the wealth of our country. Our universities are open establishments, our hospitals would not function without foreign staff," he said.
"It is this spirit of openness, embodied by the Swiss abroad and the Swiss at home, that I am inviting you to honour today."
"I wish you a harmonious and happy celebration of our National Day," he added.
Justice Minister Eveline Widmer-Schlumpf will address expatriates in Germany where she attends a National Day celebration at the Swiss embassy in the capital, Berlin.
Foreign Minister Micheline Calmy-Rey is scheduled to give a speech in a village outside Geneva near the border with France.
Other cabinet ministers will also make public appearances across the country or have published messages for August 1 on their ministry websites.
Communications Minister Moritz Leuenberger in his blog mounts a defence of direct democracy and warns against weakening relations with the European Union.
Couchepin is expected to visit the national camp of the Scout Movement southeast of Lake Zurich on Friday before he heads to his home canton of Valais for the evening.
At the end of last year there were 668,107 registered Swiss living abroad – an increase of 3.6% on 2006.
Almost a third of them are based in the European Union, mostly in France, Germany, and Italy.
The largest community of Swiss expatriates outside Europe is in the US.
Considerable numbers of Swiss abroad also live in Canada, Australia, Argentina, Brazil, Israel and South Africa.
President Pascal Couchepin heads the committee in charge of the August 1 festivities which aims to defend the "fundamental values of the Swiss".
The committee has organised events on the Rütli meadow in central Switzerland and in front of Parliament in the capital, Bern.
A range of acts are performing on Parliament Square from July 30-August 1, including Michael von der Heide, Polar, Sina, and Greis, while percussionist Pierre Favre, alpine trombonist Robert Morgenthaler, and Jean-Jacques Pedretti are giving a concert on the Rütli on National Day.
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