She was Founder of the National Retired Teachers Association and the American Association of Retired Persons, created two national organizations that provide support to older Americans to achieve independence, purpose and dignity.

An outstanding urban educator, Andrus discovered the plight of retired educators struggling to survive on meager pensions. She founded NRTA to use group strength to provide low-cost insurance programs and in 1956, the first health insurance program for educators over age 65. To meet the needs of all older Americans, Andrus founded AARP in 1958, becoming president and leading the organization's rapid growth by creating an array of programs to help mature Americans with many aspects of their lives, including second careers, health insurance, travel, and more. AARP became a powerful lobby for the needs of the aging, and Andrus, a respected expert on problems of the aging, advised government on programs and policies. She also founded and edited Modern Maturity, AARP's magazine, which has the nation's largest circulation.

Andrus lived her philosophy, helping others use their strengths and abilities throughout life.