Wilson Sonsini

Wilson Sonsini is the law firm most closely tied to Palo Alto's technology history. It was founded here in 1961, before the region had its Silicon Valley nickname. Its lawyers have incorporated, financed, taken public and sold a long list of tech and life science companies. The firm still runs from its headquarters at 650 Page Mill Road, at the edge of Stanford Research Park.

This profile covers how the firm started, the deals that made its name, how it fits into the startup world here and what a visitor needs to know. For a broader look at legal help for founders, see our guide to startup law firms in Palo Alto.

Founding in 1961

The firm began in 1961 as McCloskey, Wilson and Mosher. Its three name partners were Paul N. "Pete" McCloskey Jr., John Arnot Wilson and Roger Laurence Mosher. From the start its focus was emerging technology companies and the people who funded them.

Lawrence W. "Larry" Sonsini joined in 1966. When McCloskey left for Congress, where he served from 1967 to 1983, the firm became Wilson, Mosher and Sonsini. John B. Goodrich arrived in 1970 and built the tax department. Mario M. Rosati joined soon after to start a trusts and estates practice.

In 1978 Mosher left and took part of the firm with him. The rest adopted the name Wilson Sonsini Goodrich and Rosati. On November 6, 2019, alongside a new website, the firm began using the shorter name Wilson Sonsini in everyday use.

Deals that made its name

The firm's reputation rests on decades of work for companies at every stage. A few milestones show the range.

Over the years the firm has also worked for chip companies such as LSI Logic, Altera and Cypress Semiconductor. It represented Twitter in Elon Musk's $44 billion purchase and acted as outside counsel for Google in antitrust matters. Our Google profile covers that company's own Palo Alto years.

Equity in clients

Like several Silicon Valley firms, Wilson Sonsini has at times taken small equity stakes in clients. Wikipedia notes that its holdings in companies such as VA Linux, Ask Jeeves and Google rose sharply when those companies went public. The dot-com bust then forced layoffs of about 10 percent of its attorneys before business recovered.

Leadership over the years

Larry Sonsini led the firm as chief executive for more than 20 years and became known as a central figure in Silicon Valley law. In February 2005 John Roos, a partner who had worked with young companies for two decades, succeeded him. Roos left in 2009 when President Obama appointed him U.S. Ambassador to Japan. Steven E. Bochner followed as chief executive.

Douglas Clark became managing partner in 2012. Wikipedia reports that Clark was set to retire in August 2026 and that Caz Hashemi and Megan Baier would lead the firm as co-managing partners. Check the firm's own site for current titles.

Former Wilson Sonsini lawyers include Congressman Ro Khanna, federal appeals judge Lucy Koh and Chris Kelly, Facebook's first general counsel. Facebook's early years in Palo Alto are covered in our Facebook profile.

The Page Mill Road headquarters

The firm's headquarters is at 650 Page Mill Road. A 2022 report on its lease renewal said Wilson Sonsini has occupied the entire two-story building since it opened in 1994. The firm's careers site calls the office its headquarters and notes that it was founded before the region was called Silicon Valley.

The location makes sense. Page Mill Road ties together Stanford, the research park, El Camino Real and Interstate 280 toward Sand Hill Road. Clients in the park, investors on Sand Hill Road and Stanford faculty with startup ideas are all a short drive away. The firm's neighbor in the research park, Cooley, is another large startup law firm with Palo Alto roots.

Wikipedia lists about 1,055 attorneys and 1,973 total employees as of March 1, 2026. Beyond Palo Alto, the firm has 12 more U.S. offices and four abroad, in Hong Kong, Shanghai, Brussels and London.

Its place in Palo Alto history

Wilson Sonsini grew up with the valley around it. When the firm opened in 1961, Hewlett-Packard and Varian were the big local names. Stanford Research Park was only a decade old. Chip companies were spreading from Palo Alto toward Mountain View and Santa Clara. Venture capital was just becoming an organized business. From the start the firm focused on that new kind of client.

Its 1969 role in forming the Mayfield Fund shows how closely lawyers and investors worked together in those years. Startup lawyers drafted the partnership papers for new funds, then the documents for the companies those funds backed. Our history of venture capital on the Peninsula covers that era. Our Silicon Valley history tells the longer story.

The firm's alumni list reflects the same mix of law, business and public life. Pete McCloskey, the first name partner, spent 16 years in Congress. Later lawyers moved into company legal departments, venture firms and the courts.

Working at the firm

Wilson Sonsini hires attorneys, paralegals and business staff in Palo Alto. Its careers pages list open roles and programs for law students. Law firm hiring runs on a different calendar from tech hiring. Programs for law students are often filled many months ahead, so check the firm's site early. For a wider view of local employers and pay, see our guide to finding a tech job in Palo Alto.

What it means for founders

For a founder, a firm like Wilson Sonsini handles the paperwork that turns an idea into a company. That covers incorporation, founder stock, option plans, financing rounds, patents and eventually a sale or public offering. Large firms often defer fees for promising startups until a funding round closes. Terms vary, so ask directly.

If you are just starting out, read our guides to incorporating a startup and equity and stock options before your first meeting. You will make better use of billable time.

Visiting and nearby

The building is a private law office. There are no exhibits, tours or public spaces. Visits are by appointment only. Follow the parking and check-in instructions in your invitation. Do not use the firm's contact forms to request a tour.

The closest Caltrain stop is California Avenue, under a mile away. Caltrain runs to San Francisco and San Jose. For lunch, California Avenue has a car-free dining street where La Bodeguita del Medio has served Cuban food since 1997 and Terún makes Neapolitan pizza. Coupa Café at The Hub, 3215 Porter Drive in the research park, serves coffee and lunch on weekdays.

Frequently asked questions