This study examines the relationship between government size and economic growth in Nigeria using annually time series data for 1970 through 2010.In order to fully account for feedbacks, a vector autoregression model is utilized. The results show that there is a long-run relationship between government size and economic growth. The Forecast Error Variance Decomposition results show that the main sources of Nigeria economic growth variation are due largely to "own shocks", government size and real gross domestic product per head innovations. This study therefore recommends adoption of government activities expansion as a means of accelerating economic growth in Nigeria.