The volatile content of magma in the reservoirs of active volcanoes has an important bearing on problems of petrogenesis, magma degassing, eruption mechanisms, eruption forecasting and monitoring and the environmental impact of eruptions. Volcanic gas compositions and the S content of glasses are used to infer the volatile content and the degassing systematics of magma from the Kilauea volcano. Our results are combined with data for Kilauea's magma supply and distribution over the past 27 yr to calculate the volatile budget of the volcano.