Appreciative joy (or sympathetic joy) refers to feeling happiness for others and is one of the four prosocial attitudes ("four immeasurables") cultivated by loving-kindness meditation in Buddhism. The current study included 1622 participants and developed a scale to measure appreciative joy for friends in daily life. Both an exploratory factor analysis and confirmatory factor analysis resulted in an appreciative joy scale consisting of three components: sense of joy, positive interpersonal bias, and self-transcendence (study 1). The appreciative joy scale exhibited high correlations with measurements for interpersonal relationships and four immeasurables. The scale also shows incremental contributions to positive emotions, satisfaction with life, trait happiness, and peace of mind after controlling for interpersonal relationships or the four immeasurables (studies 2 and 3). The scale exhibited higher scores among Buddhists than among individuals with no religious belief, and its structure was maintained across English and Chinese samples (study 4); in addition, it demonstrated good test-retest reliability (study 5). Overall, the current study validated the scale as a useful tool for measuring appreciative joy, and certain findings also highlighted directions for future research on appreciative joy, including causal relationships with positive emotions, comparisons with compassion, and effects on envy.