Modifies the definitional provision at 42 U.S.C. 1437a(b)(9) to adjust formatting of the term's definition and add an explicit exclusion stating that the defined 'activity' does not include manufacture, sale, distribution, use, or possession of marijuana when that conduct is in compliance with the law of the State in which it occurs.

Multiple amendments to 42 U.S.C. 1437d: (1) In subsection (l) (the matter preceding subsection (m)), changes a cross-reference from 'paragraph (5)' to 'paragraph (6)', adjusts the formatting of a definitional provision for 'activity', and adds an explicit exclusion that 'activity' does not include manufacture, sale, distribution, use, or possession of marijuana when in compliance with the law of the State in which it occurs. (2) In subsection (t)(7)(C), adjusts the formatting of a definitional provision for 'substance' and adds an explicit clause that the definition does not include the use of marijuana (as defined in 21 U.S.C. 802) when that use is in compliance with State law.

Amends the definitional provision at 42 U.S.C. 1437f(f)(5) by adjusting the formatting of the term's definition and adding an explicit exclusion that the defined 'activity' does not include manufacture, sale, distribution, use, or possession of marijuana when such conduct is in compliance with the law of the State in which it occurs.

Amends subsection (b) of 42 U.S.C. 13661 to add a State-law exception for marijuana: public housing agencies and owners may not establish standards prohibiting admission for households with a member who engages in marijuana-related conduct that is compliant with State law; adjusts related language in paragraphs (1) and (2).

Adds a new subsection (c) to 42 U.S.C. 13662 establishing a State-law exception: the term 'illegal use of a controlled substance' does not include marijuana use, distribution, possession, sale, or manufacture that complies with State law (as defined in 21 U.S.C. 802).

Adds a new paragraph (4) to 42 U.S.C. 13664 defining the term 'State' to include the several States, the District of Columbia, Puerto Rico, Guam, American Samoa, the Commonwealth of the Northern Mariana Islands, the Federated States of Micronesia, the Republic of the Marshall Islands, the Republic of Palau, and the United States Virgin Islands.

Inserts a new section (section 580) titled 'Enforcement; smoke-free zones' which (a) defines 'marijuana' by reference to 21 U.S.C. 802, (b) prohibits the Secretary from prohibiting or discouraging activities involving marijuana in federally assisted housing that comply with State law, and (c) requires HUD to issue regulations within 90 days after enactment restricting smoking marijuana in federally assisted housing in the same manner and locations as the existing tobacco smoking restrictions under subpart G of part 965 of 24 CFR.