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About Us

Leadership Team

Chief Executive Officer, Dr. Kathleen O’Brien, Ph.D.
301-997-1300 ext 803 

Kathleen O. O’Brien, Ph.D., is CEO of Walden/Sierra, Inc. a premier behavioral health organization serving Southern Maryland. She earned her Bachelor’s and Master’s degrees from the University of Maryland, and her doctorate in Clinical Psychology from LaSalle University.

Dr. O’Brien began her long association with Walden/Sierra in 1973, serving as the Clinical Director from 1978 to 1990, when she became the Executive Director. Her commitment and dedication have been a driving force in the development and expansion of a multi-service behavioral health organization that is respected throughout the State and has received national recognition.  Read More

Clinical Services Officer, Elizabeth Lenhart-Cooksey, LCSW-C, LCADC
301-997-1300 ext 805

Betsy has been working in the clinical and administrative aspects of the substance abuse and mental health field since 1994.  She holds a MSW from the University of Maryland School of Social Work and a MA in Counseling Psychology from Bowie State College.  Betsy completed her undergraduate work at Towson State University.  She is a Licensed Certified Social Worker-Clinical (LCSW-C) and a Licensed Certified Alcohol and Drug Counselor (LCADC). Read more

Recovery Services Director, Laura Webb, M.A., A.C.E.
301-997-1300 ext 804

Laura directs Walden's Beacon of Hope (Adult) and Cove/DFZ  (Youth) Community Centers which are free and open to the public.  Both services are focused on wellness and recovery.  Laura also supervises Walden's cadre of peer support staff.  
Trained as an adult and community educator and writer, Laura is a certified instructor of Mental Health First Aid, Youth Mental Health First Aid, CCAR Recovery Coach Academy and Risking Connection.