The first documented opposition from LGBT organizations to NAMBLA occurred in the conference that organized the
first gay march on Washington in 1979.
In 1980 a group called the "Lesbian Caucus – Lesbian & Gay Pride March Committee" distributed a hand-out urging women to split from the annual
New York City Gay Pride March because the organizing committee had supposedly been dominated by NAMBLA and its supporters. The next year, after some lesbians threatened to picket, the
Cornell University gay group Gay PAC (Gay People at Cornell) rescinded its invitation to NAMBLA founder David Thorstad to be the keynote speaker at the annual May Gay Festival. In the following years, gay rights groups attempted to block NAMBLA’s participation in gay pride parades, prompting leading gay rights figure
Harry Hay to wear a sign proclaiming "NAMBLA walks with me" as he participated in a 1986 gay pride march in Los Angeles.
By the mid-1980s, NAMBLA was virtually alone in its positions and found itself politically isolated.