The 2010 discovery of offshore natural gas in Tanzania generated significant national and regional development expectations, especially in the historically marginalized region of Mtwara. Media and policy discourse framed the gas finds as transformative drivers of economic growth, positioning extractive resources as catalysts for development—a model this dissertation terms extractivist development. Yet by 2015, contractual disputes between the Tanzanian government and international oil companies, alongside global market fluctuations, led to a decline in investment and exploration. This marked a shift from the initial period of optimism—referred to as the "gas rush"—to stagnation and disillusionment. Youth were among the most affected. As key targets of Corporate Social Responsibility (CSR) programs, they were positioned as both beneficiaries and agents of development, reflecting global discourses that cast youth as a “crisis” to be managed or a resource to be mobilized. This dissertation critically examines youth development within extractivist frameworks by exploring how young people in Mtwara experienced both the promises and disappointments of the gas industry. Drawing on ethnographic fieldwork conducted from 2020 to 2022—during the “gas bust”—it analyzes how volatility in the sector shaped youth aspirations for economic independence, a key yet unstable marker of adulthood. The study argues that the gas sector’s material and temporal dynamics are deeply intertwined with youth trajectories, revealing how young people navigate constrained opportunities and contested visions of development.