This study has examined the impact of International Development Association (IDA) on the Nigerian economy for the period 1986 to 2016. The study used unit root test to determine the stationary state of the variables using the Augmented Dickey-Fuller Test. It also employs the Granger causality procedure, Johansen Co-integration and Error Correction Model (ECM) statistical techniques to establish both the direction of causality, short-run and long run dynamic relationship between the dependent and independent variables. The findings indicate that official development assistance increases the rate of economic growth of Nigerian; there is a unidirectional causal relationship between economic growth and official development assistance, i.e. the changes in the official development assistance are caused by the changes in economic growth and again, there exists a long run equilibrium relationship between official development assistance and economic growth. The study submits that the use of foreign aid should be encouraged since it promotes growth. It is therefore recommended that Government should create an enabling environment needed for investment of this official development assistance, Measures should be mapped out to ensure that every investment using official development assistance should be on capital project that will have a long term benefit and the Nigerian government should put stringent measures/policies to ensure the assistances from these body is well utilized to positively enhance both human and economic growth of the country.