Simpson Thacher & Bartlett LLP | 88,400 followers on LinkedIn. Simpson Thacher & Bartlett LLP is one of the world’s leading international law firms. The Firm was established in 1884 and has approximately 1,500 lawyers. Headquartered in New York with offices in Beijing, Boston, Brussels, Hong Kong, Houston, London, Los Angeles, Luxembourg, Palo Alto, São Paulo, Tokyo and Washington, D.C., the Firm provides coordinated legal advice and transactional capability to clients around the globe.