Phyllis Lyon and Del Martin pioneered the modern gay rights and feminist movements. They founded the first lesbian rights organization in US history, the Daughters of Bilitis (DOB), in 1955. Beginning as a small social club, the group grew into a national network with local chapters. The DOB and other organizations provided a foundation for both the lesbian and gay rights movement and the women's liberation movement of the late 1960s and early 1970s. Their efforts ushered in a new era of openness, media visibility, and political engagement for the LGBT community. This collection provides extensive information on the founding and growth of the movement through the lens of the Daughters of Bilitis and The Ladder, DOB's monthly magazine. Documents include materials on DOB's beginnings and development; annual organizational histories published in The Ladder; early meeting minutes; correspondence; records of local chapters; presentations to gay rights organizations; membership data; and manuscripts unavailable elsewhere. The collection also contains a complete run of The Ladder (1956-1972) which began as a mimeographed newsletter and grew into an internationally circulated magazine with thousands of subscribers. Providing one of the few media outlets produced by lesbians and for lesbians, the periodical challenged misogyny as well as homophobia.