This lecture explores preference-based assessment in valuation methods, focusing on translating preferences into monetary values using concepts like willingness to pay (WTP) and willingness to accept (WTA). It delves into personal improvements and deteriorations, two families of assessment methods (Revealed Preferences and Stated Preferences), and various approaches within these families. The lecture further discusses the Travel Cost method, Hedonic Price method, and the Contingent Valuation method, providing examples and explaining the fundamental assumptions behind each method. Additionally, it covers the hedonic assessment of WTA risk in wages and the problems associated with the Contingent Valuation method, such as designing truthful scenarios and estimating non-use values.