Essays on investment and house prices TranThang Long 2017 This thesis combines four related essays that examine investment activities and housing dynamics in Australia. The first essay investigates the key drivers of Australian aggregate business investment. Tobin’s q, income, cash flow and uncertainty impacts on investment are determined and disentangled. Uncertainty and demand constraints are revealed to be highly significant for investment over business cycle frequencies. The second essay examines the firm-level investment determinants of listed non-financial companies in the Australian stock market. Although both having negative effects on firm investment, firm specific uncertainty is more important in explaining firm investment than macroeconomic uncertainty. The third essay analyses the price dynamics of the Australian housing market during the last three decades using a housing behavioral economic model based on nominal variables and the behavior of house buyers. The empirical evidence shows that the proposed model is equivalent or even better than other conventional models in explaining house price dynamics. In the last essay, private housing investment in Australia since the 1980s is investigated using Tobin’s q and stock-flow models. A long-term co-integration relationship between Tobin’s q and the investment ratio, as posited by q theory is not found, while changes in q have an impact on investment in the short-term. The determinants extracted from the stock-flow model explain the movement of housing investment. Uncertainty and construction costs are revealed not to be highly significant for investment. There is evidence of a positive correlation between investment and business cycles.