Many commentators claim a key role for the private sector in reducing poverty. This can be achieved through direct benefits, such as the adoption of ethical business practices and the provision of employment, goods, and services to the poor; and through indirect positive impacts on macro-economic policy and business development. This paper argues that the likelihood of business impacts being pro-poor depends also on wider policy and structural conditions. These include the importance of poor people in a company's business model, and the length of local investment and commitment that this demands. Case studies of three companies demonstrate the importance of legislation and civil society as catalysts for pro-poor change in business. Leadership from within the company and a strong business case are also essential. However, multiple entrenched problems with modern capitalist systems work against positive change within international business. Overcoming or mitigating these will be necessary if the pro-poor potential of the private sector is to be realised.