In 1920, twenty million American women won the right to vote. The League of Women Voters was established the same year to enable these newly-enfranchised women to promote political responsibility through informed and active participation in government. In 1974, men were granted full membership in the League. Non-citizens may participate as associate (non-voting) members.

The League of Women Voters is a non-partisan organization. It does not support candidates or political parties. Rather, the League supports issues, studying them in depth and reaching agreement (consensus) on action. When the League adopts a position on an issue, it takes action with the appropriate government agency.

The League of Women Voters of Waltham, formed in 1942, is composed of women and men, citizens and non-citizens. Any resident aged 18 or older is welcome to join. Membership in the Waltham League automatically confers membership in both the Massachusetts League and the The League of Women Voters of the United States.