Firm History

Armstrong Teasdale has a rich history with more than 120 years of experience counseling clients through their most complex legal challenges. Over the past century, the firm has grown tremendously and now boasts more than 600 lawyers and business professionals across 18 offices.


Business lawyers Thomas Harper Cobbs (pictured) and John E. Bishop form a law partnership, Bishop and Cobbs, in St. Louis on Jan. 1, 1901.


New partners are added regularly in the early years. In 1927, William Armstrong joins as an associate. He becomes a partner in 1931 and Armstrong is added to the firm name in 1939.


Kenneth Teasdale, a good friend of William Armstrong and well-known St. Louis-based trial lawyer, joins the firm. In 1949 Teasdale is added to the firm name.


William H. Webster joins the firm. After leaving in 1970, he goes on to serve as a judge for the U.S. District Court for the Eastern District of Missouri, the U.S. Court of Appeals for the Eighth Circuit, and is to date the only person to have served as director of both the FBI and the CIA. In 2024, the firm dedicated its Executive Conference Room in St. Louis in his honor.


Kenneth Teasdale’s son, Kenneth S.F. Teasdale, joins the firm after a distinguished career in Washington, D.C. with the U.S. Department of Justice.


Steve Cousins is named the first African-American partner at the firm. In 2018, Steve retired from AT and now serves as president and CEO of affiliate Cousins Allied Strategic Advisors, LLC.


The firm merges with the St. Louis firm Schlafly, Griesedieck, Toft & Virtel, becoming Armstrong, Teasdale, Kramer, Vaughan & Schlafly. The firm grows to 83 lawyers. By end of the following year, we are the third-largest law firm in the St. Louis area based on the number of lawyers.


Kansas City office opens upon a merger with a local firm.


Jefferson City, Missouri, office opens.


The firm’s Professional Advancement of Women program is established; today called the Women’s Inclusion Network. The program is one of the first of its type at a private law firm in the St. Louis region.


The firm became an LLP and shortened its name – a sweeping trend in the legal industry – to Armstrong Teasdale.


The firm establishes the Michael C. Tramble Memorial Scholarship Fund at the University of Missouri School of Law, in memory of a promising young African-American associate at the firm who tragically lost his life.


Las Vegas office opens.


The firm is named to the Am Law 200, a list of the 200 largest law firms in the U.S. as ranked by The American Lawyer.


Denver office opens, with the acquisition of a Denver-based firm.


Armstrong Teasdale expands to the East Coast with the opening of its Philadelphia office.


New York office opens with one of the largest real estate practices focusing on cooperative/condominium law in the city. Since 2019, the office has grown to include prominent lawyers across practice areas.


Offices open in Boston, Salt Lake City (pictured), and Edwardsville, Illinois.


The firm establishes a dedicated Diversity, Equity and Inclusion department as an additional investment based on the long-standing success of the firm’s Inclusion Committee..


Wilmington, Delaware, office opens.


The firm establishes a presence in the U.K. with the addition of over 50 lawyers and business professionals in London.


The firm establishes a presence in Florida with the addition of 12 lawyers and business professionals in Miami.


The firm establishes a presence in the EU with the opening of an office in Dublin, Ireland.


Washington, D.C., office opens.


The firm expands its western U.S. presence with the establishment of an office in Orange County, California.


Nearly 50 lawyers and business professionals join Armstrong Teasdale from a boutique litigation firm, establishing an office in Chicago.

Contact Us
  • Worldwide
  • Boston, MA
  • Chicago, IL
  • Denver, CO
  • Dublin, Ireland
  • Edwardsville, IL
  • Jefferson City, MO
  • Kansas City, MO
  • Las Vegas, NV
  • London, England
  • Miami, FL
  • New York, NY
  • Orange County, CA
  • Philadelphia, PA
  • Princeton, NJ
  • Salt Lake City, UT
  • St. Louis, MO
  • Washington, D.C.
  • Wilmington, DE
abstract image of world map
Boston, MA
800 Boylston St.
30th Floor
Boston, MA 02199
Google Maps
Boston, Massachusetts
Chicago, IL
100 North Riverside Plaza
Suite 1500
Chicago, IL 60606-1520
Google Maps
Chicago, Illinois
Denver, CO
4643 S. Ulster St.
Suite 800
Denver, CO 80237
Google Maps
Denver, Colorado
Dublin, Ireland
Fitzwilliam Hall, Fitzwilliam Place
Dublin 2, Ireland
Google Maps
Edwardsville, IL
115 N. Second St.
Edwardsville, IL 62025
Google Maps
Edwardsville, Illinois
Jefferson City, MO
101 E. High St.
First Floor
Jefferson City, MO 65101
Google Maps
Jefferson City, Missouri
Kansas City, MO
2345 Grand Blvd.
Suite 1500
Kansas City, MO 64108
Google Maps
Kansas City, Missouri
Las Vegas, NV
7160 Rafael Rivera Way
Suite 320
Las Vegas, NV 89113
Google Maps
Las Vegas, Nevada
London, England
Royal College of Surgeons of England
38-43 Lincoln’s Inn Fields
London, WC2A 3PE
Google Maps
Miami, FL
355 Alhambra Circle
Suite 1200
Coral Gables, FL 33134
Google Maps
Photo of Miami, Florida
New York, NY
7 Times Square, 44th Floor
New York, NY 10036
Google Maps
New York City skyline
Orange County, CA
19800 MacArthur Boulevard
Suite 300
Irvine, CA 92612
Google Maps
Philadelphia, PA
2005 Market Street
29th Floor, One Commerce Square
Philadelphia, PA 19103
Google Maps
Philadelphia, Pennsylvania
Princeton, NJ
100 Overlook Center
Second Floor
Princeton, NJ 08540
Google Maps
Princeton, New Jersey
Salt Lake City, UT
222 South Main St.
Suite 1830
Salt Lake City, UT 84101
Google Maps
Salt Lake City, Utah
St. Louis, MO
7700 Forsyth Blvd.
Suite 1800
St. Louis, MO 63105
Google Maps
St. Louis, Missouri
Washington, D.C.
1717 Pennsylvania Avenue NW
Suite 400
Washington, DC 20006
Google Maps
Photo of Washington, D.C. with the Capitol in the foreground and Washington Monument in the background.
Wilmington, DE
1007 North Market Street
Wilmington, DE 19801
Google Maps
Wilmington, Delaware