The paper seeks to model the long run determinants of domestic private investment in Nigeria over the period 1970 to 2010, employing advanced econometric technique of Auto-Regressive Distributed Lag (ARDL) bounds testing approach. Emanated from the estimated models are intriguing findings which showed clearly that difference exist between long and short run determinants. Public investment, real GDP, real interest rate, exchange rate, credit to the private sector, terms of trade, external debts and reforms dummy are the key long run determinants of domestic private investment while public investment, real GDP and terms of trade are statistically significant in the short run. The policy prescriptions are that necessary infrastructures to complement domestic private investment should be put in place; that external debts be reduced to the barest minimum and negative effects of external shocks engendered by foreign direct investment uncertainty and deficit terms of trade should be prevented altogether.