Toni N. Harp took office on Wednesday as New Haven’s 50th mayor — the city’s first female chief executive in its 375-year history.

Harp, an 11-term state senator, succeeds John DeStefano Jr., whose two decades in the mayor’s office have left an indelible mark on the city he governed. In an assertive, 33-minute address, Harp rebutted the notion that New Haven is a city in decline, emphasizing its diverse strengths as a bedrock of progress.

“With all due respect for New Haven’s extraordinary history … I am more excited about New Haven and its prospects for the next two years,” Harp told the roughly 750 people crowded into the auditorium of Hill Regional Career High School. “Our collective potential is positively inspiring.

Harp, 64, was officially sworn in as mayor by retired Connecticut Supreme Court Justice Lubbie Harper Jr. City Clerk Michael Smart and the 30 members of the Board of Alders — six of whom began their first term in office Jan. 1 — also took their oaths of office at the noon ceremony.

Promising renewed prosperity for the city she has represented in Hartford since 1993, Harp said that New Haven has the potential to become a statewide — and even national — model if it invests in burgeoning sectors of the economy, such as biotechnology and healthcare, and ensures that city residents get jobs in those fields. She said her administration will strive to end the drain of existing business out of New Haven while working to encourage new ventures that promise to put city residents to work.

While endorsing intracity hiring, she said New Haven should look outward in harnessing the economic potential of the regional northeast and seek to enter markets that wind their way through New York City and other hubs of economic activity.

The linchpin of the city’s economic development strategy, she said, is promoting a “safe, enjoyable, livable city,” a vision she spent the majority of her remarks outlining.

Crime prevention, healthcare and nutrition, STEM-focused education improvements and infrastructure developments will govern her agenda as mayor, Harp forecast. Among a slew of policy priorities, Harp specifically pledged to rebuild the sagging Pardee Seawall along the East Shore, which protects waterfront properties from the Long Island Sound.

Harp also extolled the virtues of community policing — saying she and New Haven Police Chief Dean Esserman both put “crime prevention on equal footing with law enforcement” — and encouraged empathy for individuals who make choices that contravene the law.

“No first grade student, when asked what he or she wants to be when grown up, answers embezzler, drug dealer, or murderer,” Harp said. “I’m confident that the vast majority of those who commit crimes do so out of desperation, not as a career destination.”

Insisting that her view should not be mistaken for being “soft on crime,” she said community policing has already seen promising results in curtailing violent crime, as well as in enabling “redemption and rehabilitation.”

With sustainable public services,  such as a redeveloped and reopened Dixwell Q House community center, young people can be turned away from crime, Harp said. Similarly, she said no New Haven residents should suffer from debilitating illnesses or chronic malnutrition when the institutions and services exist to care for them.

Sworn in as mayor the same day that more than 34,000 Connecticut residents became eligible for coverage under the Affordable Care Act, Harp said she would seek to further the goals of preventative care and early treatment in New Haven. She called it an “egregious moral failure” that city residents would be denied care by “one of the world’s foremost medical centers,” referring to Yale-New Haven Hospital.

Harp also promised a brighter future for the malnourished; 20 percent of Greater New Haven residents said they did not have enough money to buy food in Fall 2012, according to a 2013 community index report by the nonprofit DataHaven. She said the government has a role to play in ensuring no neighborhood becomes a “food desert,” left without adequate nutritional resources.

Harp paid brief homage to DeStefano’s 20-year tenure, promising to build on his accomplishments at the city’s helm. She also gave a nod to her legislative counterpart, congratulating the newly elected alders, a majority of whom backed her campaign, and saying she was “glad to have fallen in step with you for this next term.”

The inaugural ceremonies were directed by Karen DuBois-Walton, chief of the New Haven Housing Authority. The event featured remarks by members of New Haven’s federal and state delegation, as well as multi-faith prayers and performances by local musical groups.

Connecticut Gov. Dannel Malloy and U.S. Senators Richard Blumenthal LAW ’73 and Chris Murphy praised Harp as a compassionate and effective leader, saying she was known as the “conscience of the state senate.”

Malloy said Harp will lead New Haven with “the biggest heart you can possibly have” and “one of the greatest minds that have served the state of Connecticut.” He promised cooperation on redevelopment plans such as the Coliseum project and the revitalization of Union Station.

The historical significance of Harp’s installation as the first female — and only second African-American — head of the city infused the ceremonies. Nearly all of the speeches leading up to Harp’s highlighted her status as a trailblazer for minorities and women in New Haven.

The theme of inclusiveness was not lost on audience members, who expressed admiration for Harp’s commitment to choosing what one attendee, Ronald Williams, described as an “administration mirroring the city.” Yusuf Shah, a former Ward 23 alder, said Harp has begun her tenure wisely, correctly identifying “the blemishes we have in our city.”

City dignitaries were joined by high-level members of the Yale administration in celebrating Harp’s inauguration, including University President Peter Salovey and Vice President of New Haven and State Affairs Bruce Alexander ’65.

Yale President Peter Salovey said he particularly appreciated Harp’s focus on economic development and community policing, citing the issues as areas where the city and University can collaborate.

Despite Wednesday’s optimism, Harp’s first weeks and months in office will likely revolve around the more nitty-gritty matters of filling out her administration and grappling with the city’s budget, which is due by March. Those, and others, will be no easy tasks, Harp acknowledged.

“To get it all done, we must put aside our differences,” she said. “We must work together.”

Harp was joined on stage by her three children: Matthew, Jamil and Djana.