NAYPYIDAW, Myanmar — Dressed in flowing purple silk, Daw Aung San Suu Kyi climbed the stone steps of Parliament here Wednesday, delicate and serene in the face of a mob of photographers as she prepared to create a milestone for her country.

Ms. Aung San Suu Kyi, who was awarded the 1991 Nobel Peace Prize for her opposition to military rule, appeared characteristically understated. “Perhaps I’m not a very emotional person,” she told reporters.

After two decades of persecution as Myanmar’s most prominent dissident, she and nearly three dozen members of her party, the National League for Democracy, took the parliamentary oath of office. The hall was dominated by the green shirts of soldiers, who under the Constitution make up 25 percent of Parliament, and the white shirts of the country’s most powerful political party, the Union Solidarity and Development Party. Still, former political prisoners in rust-colored jackets sat alongside the former generals who had jailed them.

The session itself was pro forma, with Ms. Aung San Suu Kyi and her fellows — 8 percent of the Parliament — standing to vow to “uphold and abide by the Constitution of the Union.”