This article describes key concepts, reviews empirical findings, and discusses important issues related to the use of subjective importance ratings and importance weighting. The review of empirical findings focuses on weighting achieved via the multiplicative model and on 3 areas in which weighting is commonly used: quality of life, self-esteem, and job satisfaction. An important distinction is made between issues regarding importance ratings and those related to importance weights. Directions for future research are suggested throughout the article.