This document discusses factors that influence the effectiveness of aid in promoting growth, reducing poverty, and increasing private investment. It finds that aid works best in countries with good economic management policies. Countries with stable macroeconomic policies and strong institutions see aid increase growth by 0.5% of GDP and private investment by 1.9% of GDP. However, aid has little impact in countries with poor economic management and weak institutions. The document also notes that bilateral aid allocation is often influenced by political interests rather than economic conditions, while multilateral aid focuses more on countries with good policies. For aid to be most effective, it recommends targeting the "high impact countries" that have both high poverty and good economic policies.