The laws governing the legal use, storage and carrying of firearms are constantly changing. Below are the applicable laws in the State of Washington as of 3/01/2013. The below information is designed to be a guide and not the final word. If you have specific questions, please refer to the Washington State legislation at apps.leg.wa.gov. Another great resource is the Washington Department  of Licensing dol.wa.gov.

1)(a) A person licensed to carry a pistol in a state the laws of which recognize and give effect in that state to a concealed pistol license issued under the laws of the state of Washington is authorized to carry a concealed pistol in this state if:
(i) The licensing state does not issue concealed pistol licenses to persons under twenty-one years of age; and
(ii) The licensing state requires mandatory fingerprint-based background checks of criminal and mental health history for all persons who apply for a concealed pistol license.

    (b) This section applies to a license holder from another state only while the license holder is not a resident of this state. A license holder from another state must carry the handgun in compliance with the laws of this state.
     (2) The attorney general shall periodically publish a list of states the laws of which recognize and give effect in that state to a concealed pistol license issued under the laws of the state of Washington and which meet the requirements of subsection (1)(a)(i) and (ii) of this section.

Washington honors Resident and Non-Resident Concealed Carry Permit/License from the states listed below:
Arkansas, Florida, Louisiana, Michigan, Mississippi, Missouri, North Carolina, North Dakota, Ohio, Oklahoma, Tennessee, Utah

The states listed below honors the Resident Washington Concealed Pistol License:
Alaska, Arizona, Arkansas, Florida, Idaho, Indiana, Iowa, Kentucky, Louisiana, Michigan, Mississippi, Missouri, Montana, North Carolina, North Dakota, Ohio, Oklahoma, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, Wisconsin

The states listed below honors the Non-Resident Washington Concealed Pistol License:
Alaska, Arizona, Arkansas, Idaho, Indiana, Iowa, Kentucky, Louisiana, Mississippi, Missouri, Montana, North Carolina, North Dakota, Ohio, Oklahoma, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, Wisconsin