However, information about public interest in developing marine renewable energy technology, including tidal energy technology, in WA and the U.S. has been limited. Responses to a dichotomous choice referendum question on a mail survey sent to a representative sample of WA households were used to estimate residents' Willingness To Pay (WTP) for tidal energy R&D.Public preferences for policies to support tidal energy R&D were also assessed. WA households are WTP a median of $1.62 per month for tidal energy R&D, indicating public preference for an increase in public spending on tidal energy R&D over current levels. Public perceptions of potential social, environmental, and economic risks and benefits of developing tidal energy emerged as highly significant predictors of WTP.i