Drawing on challenges she has faced as Africa’s first elected female head of state, Liberian president Ellen Johnson Sirleaf urged Harvard’s Class of 2011 to be hopeful, resilient, and daring in facing life’s obstacles.

Sirleaf—who delivered her remarks at the Afternoon Exercises of the Commencement ceremony Thursday—struck a tone that many audience members described as optimistic and inspiring.

“If your dreams do not scare you,” she told a crowd of thousands of recent graduates and alumni, “they are not big enough.”

Sirleaf, who is up for reelection this November, spent much of her speech discussing her administration’s accomplishments during her first six-year term.

“In five years, we formulated the laws and policies and strategies for growth and development,” she said.

Since taking office in 2006, Sirleaf, a Harvard Kennedy School alumna, said she has nearly eliminated the country’s $4.9 billion external debt; increased national revenue by over 400 percent; restored electricity and tap water to Monrovia, the Liberian capital city; and reconstructed universities, schools, and hospitals.

Yet despite these successes, Sirleaf acknowledged the “awesome” challenges facing Liberia, including civil war in neighboring nations, high costs, and lingering governmental inefficiency and corruption.

Sirleaf—whose reelection bid is being challenged by Winston A. Tubman, a Harvard Law School graduate—praised the “truly free and fair” election process that has been established in Liberia.

She joked that regardless of whether she or Tubman is elected, “the relationship between Harvard and Liberia is thus secured and in good hands.”

Sirleaf also championed the power of women in shaping social change, calling attention to the Liberian women who “fought the final battle for peace” by demonstrating in support of an end to Liberia’s civil war.

While she praised the 2008 presidential election of Barack Obama as one that permanently transformed the American political landscape, she gently chastised the United States for not having yet elected a female president.

“Let me remind you, America, that Liberia has you beat on one score: We elected our first female president, perhaps 11 years before the United States might do so,” she said to an appreciative laughter.

Sirleaf closed her speech by urging graduates to aim high and resist cynicism even in the face of “ample opportunity to become jaded and cynical.”

Allan S. Bradley ’11 said he was particularly moved by Sirleaf’s admonishment against cynicism, adding that her sentiment “means a lot given the questions that we as graduates are asking ourselves.”

Last year former Supreme Court Justice David H. Souter ’61 delivered the Commencement address. Comedian Amy Poehler delivered this year’s Class Day speech Wednesday.

—Staff writer Rebecca D. Robbins can be reached at rrobbins@college.harvard.edu.