Divestment has been a feature of the investment industry for decades. Attention has returned with the growth of the fossil fuel divestment campaign, among other recent environmental and social events. But what does divestment seek to achieve and does it work in practice? We carried out an objective assessment to find that it is not necessarily the most effective way to drive real change. We propose a new model for asset owners to drive change that centers on engagement and restricting the marginal supply of capital.