Sidney Armstrong is a consultant who lives and works in Helena, Montana. 

She was Executive Director of the Montana Community Foundation from 1990 to December, 2001. During its first 13 years the foundation grew to $36 million, gaining national recognition for its work in rural economic and community development and in public policy work. An important collaboration was the result of MCF's leadership in involving an earlier Montana Governor, who created a Governor's Task Force on Philanthropy, was the keynote speaker for Conversations on endowed philanthropy, and supported the passage of unique tax credit legislation for charitable endowments.

Armstrong was a member of the national Committee on Community Foundations for the Council on Foundations. She has worked with national and regional foundations and presented at numerous conferences and workshops.  She served for eight years on the staff of Montana Governor Thomas L. Judge, and later was Aide to the President and Assistant Secretary of the Montana Senate during two legislative sessions.   She is also part of the administration of Montana Governor Brian Schweitzer, serving first as a member of his Transition Team, in 2004, then temporarily as part of his immediate staff and now as a volunteer Advisor. In November 2006, she served as a coordinator for the Governor’s Conversation on Endowments and Philanthropy.

Long active in community affairs, she is a board member of Humanities Montana, the Holter Art Museum and the Lewis and Clark Co. Community Foundation, where she is chair of the grants committee. She is past president of the Helena Rotary Foundation and served on the Governor's Task Force on Endowments and Philanthropy. She is a graduate of the International School of Geneva, Switzerland and the University of MT. A native Montanan, Armstrong's Irish immigrant maternal great-grandparents, came to Montana in a covered wagon in the early 1860's, looking for gold. Eventually they settled on the banks of the Missouri River outside Helena as ranchers. Her late father, Associated Press newsman Richard K. O’Malley, grew up in the mining city of Butte and his book, Mile High, Mile Deep, recounting his youth, has just been republished by well-known painter and publisher, Russell Chatham. She is the mother of four and the grandmother of eight.