A campaign by the Independent Commission Against Corruption, begun in 1994, led to over 1,600 Hong Kong companies and trade associations adopting codes of ethics by December 1996. This study analyzed motives for code adoption; code content; how codes were developed, supported and enforced; and code impact. Primary data was collected through cross-sectional and longitudinal surveys, semi-structured interviews, observation, and document analysis. Press cuttings and published statistics were also used. Main findings were that some best practice prescriptions for code adoption were not followed, but that codes nonetheless helped preserve ethical standards and an anti-corruption image. Directions are suggested for further research into cultural effects on business ethics policy, practice and effectiveness.