This study examines the test-retest reliability of two methods of establishing health preference weights and assesses the effectiveness of a brief values-clarification exercise. Survey participants were randomly allocated to one of two groups and received either a standard protocol for eliciting health preferences (comparison group) or an augmented protocol designed to encourage reflection and deliberation (intervention group). Preferences were elicited on three occasions over 5 weeks. The results show that the two valuation methods each had acceptable levels of test-retest reliability. No significant differences were found in preference weights over time or between intervention and comparison groups. The values-clarification exercise had some impact on individual answers, but the changes cancelled each other out at the group level. There was no discernable intervention effect at the group level. It is premature to draw conclusions from one study about why, or even how, a person's valuations might change over time, but our results support the use of current valuation techniques for group-level analyses.