This thesis examines the countercultural politics expressed within the work of the American novelist Thomas Pynchon, contributing to critical work already published on the subject of Pynchon's politics, in which there has been a recent upsurge of interest. Expressions of sympathy with anarchist and anti-Capitalist principles discerned in Pynchon's work are explored in their connection with the author's experience of particular practices and philosophies of the 1960s counterculture. Furthermore, the ongoing significance of sixties politics in Pynchon's more recent production is demonstrated as ideological connections between earlier and later novels are traced. In Slow Learner Pynchon professed admiration for the motive energy of Beat literature, so influential on the formation of the counterculture. With particular focus on Jack Kerouac's On the Road, chapter one demonstrates the impact of the Beat movement, and its limits, in Pynchon's early novels. New Left thought and tactics as manifested across the decade provide the focus of the second chapter, which engages primarily with Gravity's Rainbow's depiction of Communist revolutionaries in Weimar-era Germany. The following chapter considers the role of psychedelic experience and the philosophies of Timothy Leary in Pynchon's The Crying of Lot 49 and Against the Day, arguing that the fantastical has a concrete political role in Pynchon's novels. Black Power, and specifically the political theory of the Black Panther Party, is the subject of chapter four. Gravity's Rainbow's framing of Huey P. Newton's concept of “revolutionary suicide” is central to an analysis which offers insights into the novel's perspectives on the use of violence and on leadership in revolutionary groups. The final chapter investigates the dynamics of Pynchon's ambivalent engagement with the Women's Movement. Betty Friedan's The Feminine Mystique is put forward as an important intertext for The Crying of Lot 49, while Vineland is examined in the context of radical feminism.