San Francisco Zoo appoints Cassandra Costello as chief executive, ending months of interim leadership changes

Leadership change follows a turbulent period for the nearly century-old city institution

The San Francisco Zoo & Gardens has appointed Cassandra Costello as its permanent chief executive officer and executive director, formalizing a leadership transition that began after the departure of longtime CEO Tanya Peterson. Costello had been serving in an interim leadership capacity after joining the organization as chief operating officer in 2025.

The move places a City Hall veteran at the helm of a public-facing cultural institution that has faced sustained scrutiny in recent years, including questions from city officials and advocates about animal care practices, workplace safety, and governance. The zoo is owned by the City and County of San Francisco and operated by the nonprofit San Francisco Zoological Society under a longstanding public-private partnership.

What’s known about Costello’s background and the zoo’s governance structure

Costello’s career spans public administration and the nonprofit sector in San Francisco, including leadership roles connected to tourism and city departments. She was brought to the zoo during a period when the organization was under pressure to stabilize operations and restore public confidence.

The zoo’s board has, at times, relied on shared executive leadership during the transition. Board materials have listed Costello alongside another co-chief executive during the interim period, reflecting a governance approach designed to maintain continuity while longer-term decisions were made.

Context: Peterson’s departure and the issues that intensified oversight

Peterson, who led the zoo for nearly two decades, announced her retirement in mid-2025 after mounting criticism and political pressure for leadership change. Her tenure included both capital improvements and persistent controversy. In the months leading to her exit, city officials publicly urged the zoo’s governing board to develop a plan to install new leadership.

Multiple lines of concern converged during that period, including workplace safety issues raised by employees and union representatives, and broader debates about facility conditions and animal welfare expectations at urban zoos. Federal oversight also remained part of the public discussion, with inspections serving as a baseline measure even as local critics argued for higher operational standards.

What comes next: operational priorities and public expectations

Costello assumes the permanent role as the zoo approaches its 100th anniversary and as conversations continue about potential upgrades to aging infrastructure. Leadership will also face practical challenges common to major attractions: attendance, revenue stability, staff retention, and donor confidence—alongside the specialized demands of animal care and conservation programming.

Public attention is expected to remain high, particularly as city leaders and community stakeholders continue to weigh how the zoo should balance recreation, education, conservation goals, and transparency in operations.

• New CEO named after months of interim leadership following the previous director’s retirement.
• Transition unfolds amid continuing scrutiny of safety, governance, and animal care standards.
• Renovation needs and long-term planning remain central issues as the zoo nears its centennial.

The appointment formalizes a shift toward new management at one of San Francisco’s most visible public institutions.