Explores the new provisions for the licensing of houses in multiple occupation (HMOs) and the likely effects on landlords, agents and tenants in the second of series of articles on aspects of the Housing Act 2004. Outlines the three main licensing schemes to be introduced under the Act: mandatory HMO licensing, additional HMO licensing and selective licensing. Defines an HMO. Looks at the controversial household classification and the complex situation of flats within a larger building. Examines the penalties for controlling or managing an HMO, which should be licensed but is not and passporting and temporary exemption. Lists the exemptions from the HMO definition. Advises on obtaining a licence, the contents of a licence, revocation conditions and the right to appeal. Concludes that these provisions will affect all aspects of residential letting with some landlords and many professional agents likely to withdraw from the HMO sector. Timetable of expected introduction of the provisions.