[Excerpt] In The Promise and Limits of Private Power, Richard Locke analyzes and evaluates private sector corporate social responsibility (CSR) initiatives on working conditions in global supply chain factories. The book synthesizes findings from a multi-year project that has already generated several important articles on various aspects of supply chain labor dynamics. The book is structured around a strong central theme. Corporate codes of conduct and other private, voluntary steps indeed can have some positive effects on working conditions in supply chain factories, but results are mixed. They are not sufficient for sustained improvements. Public regulation through effectively enforced legal standards must be part of the equation. In sum, "private voluntary regulation can best succeed when 'layered' on and interacting with public (state) regulation."