WA Legislature - Conference Committee Meeting

Concurrence, Dispute, and Conference Committees: If the bill has been amended by the second house, the first house has to decide whether it will concur in the amendments or not... If the two houses cannot resolve their differences, one of them can ask for a conference committee. Members from each house meet to discuss the differences. If they agree on what is to be done, the conference committee makes a report. Both houses must adopt the conference committee report for the bill to pass the Legislature. If one house does not adopt the conference committee report (whether by vote or inaction), the bill has not passed. The House Floor Activity Report and the Senate Floor Activity Report list the bills on the concurrence, dispute, and conference calendars.

Washington State Legislature - "Overview of the Legislative Process"