In 1866, Chicago was stirring with a sense of renewal. The Civil War had ended, and the city was rebuilding with a forceful energy that came from railroads, manufacturing yards, and the rapid movement of goods and people. In the middle of that momentum, two young lawyers, Norman Williams and John Leverett Thompson, opened a small office to help guide the legal issues emerging from this economic rebirth. They knew the city’s growth would demand clear counsel, steady judgment, and an understanding of how business and law would shape one another.
Their early work reflected the pulse of a city in transition. Companies tied to transportation, telecommunications, and industrial equipment turned to Williams and Thompson for help with contracts, disputes, and corporate planning. As Chicago expanded, so did the firm’s reputation for careful analysis and steady guidance.
Building the Foundation: Sidley and Austin LLP Arrive
The firm’s next defining chapter began in 1892, when William Pratt Sidley joined and became one of its central figures. His strong grasp of business law helped broaden the firm’s capabilities during a period when corporations were growing rapidly, and regulation was taking new forms. In 1914, Edwin C. Austin joined, adding his own legal strength and forming the partnership that would give the firm its lasting name: Sidley Austin LLP.
These early decades set the tone for the firm’s approach, measured expansion, deep client relationships, and a belief that legal work must evolve alongside the industries it serves.
Expanding Beyond Chicago
By the mid-20th century, Sidley Austin LLP recognized that national regulatory developments required a stronger presence beyond its hometown. In 1963, Sidley opened a Washington, D.C. office, positioning itself at the center of federal law and policy. This move marked a turning point that allowed the firm to handle more complex regulatory and government-facing matters.
Over the next several decades, Sidley Austin LLP extended its reach to financial hubs and international markets. Offices in New York, London, Brussels, Hong Kong, Singapore, and other major cities followed. A significant milestone came in 2001 with Sidley’s merger with Brown & Wood, a firm known for its capital markets and securities expertise. The combination strengthened Sidley’s position in global finance and deepened its capabilities during a period when cross-border transactions were becoming more common.
A Global Footprint
Today, Sidley Austin LLP operates with more than 2,300 lawyers across 21 offices worldwide. Its headquarters at One South Dearborn in Chicago stands as the center of a network that supports clients across industries such as financial services, life sciences, energy, healthcare, technology, and consumer products.
The firm’s services span litigation, mergers and acquisitions, regulatory advice, banking and finance, investigations, capital markets, and Supreme Court advocacy. This range allows Sidley to serve multinational companies whose legal challenges often cross jurisdictions and regulatory frameworks.
Leadership for a Modern Era
Sidley Austin LLP’s leadership today reflects both continuity and forward focus. In May 2025, Brian J. Fahrney became Chair of the Executive Committee, assuming responsibility for guiding the firm’s strategy while continuing his own practice in mergers and acquisitions, securities matters, and corporate governance. His experience advising public and private companies gives him a clear perspective on how legal needs evolve in fast-changing markets.
Working alongside him is Yvette Ostolaza, Chair of the Management Committee. She is the first woman and the first Hispanic person to hold this senior leadership role at Sidley. Her responsibilities include overseeing operations across Sidley Austin LLP’s global offices and shaping long-term priorities. Her appointment represents a milestone in the firm’s history and underscores its commitment to broadening leadership representation.
Reputation and Achievements
Sidley Austin LLP consistently ranks among the top law firms in the United States and internationally. In 2024, the firm reported approximately $3.4 billion in revenue, a figure that reflects both its size and the complexity of matters it handles. Its lawyers frequently appear in leading legal directories and publications for work in high-stakes litigation, sophisticated transactions, and major regulatory matters.
But Sidley’s recognition extends beyond business results. The firm has built a strong pro bono tradition, supporting civil rights initiatives, immigration cases, nonprofit organizations, and underserved communities. Pro bono work has long been part of Sidley’s identity, reflecting the belief that legal expertise carries broader responsibilities.
Firm Culture and Values
Sidley’s culture has remained grounded in professionalism, respect, and collaboration. Its internal programs focus on mentorship, diversity, and training that prepares lawyers for long-term careers. The firm emphasizes the idea that strong client service starts with building strong teams, an approach that echoes the values Williams and Thompson upheld more than a century and a half ago.
As Sidley Austin LLP moves forward, the firm continues to expand in areas where client needs are growing, such as technology, private equity, regulatory counseling, cross-border deals, and complex disputes. Both Fahrney and Ostolaza have emphasized the importance of staying adaptive while preserving the principles that shaped Sidley’s past: careful judgment, strategic insight, and a commitment to excellence.
A Story Still Being Written
What began in a small Chicago office in 1866, while the city rebuilt itself with determination, has evolved into a global legal institution. Sidley Austin’s story stretches across countries, industries, and generations. Still, its foundation remains the same: thoughtful legal work, steady leadership, and a belief that integrity is not a slogan but a daily practice.
From its earliest days advising the industries that built modern Chicago to its role today in shaping global legal outcomes, Sidley’s journey continues, grounded in the values that first brought Williams and Thompson together more than 150 years ago.
