This chapter describes the Self-Other Four Immeasurables (SOFI) scale (Kraus & Sears, 2009), an assessment tool for the so-called four immeasurable qualities at the heart of Buddhist teachings. These four immeasurables include loving kindness, compassion, joy, and equanimity. To evaluate these qualities, the SOFI includes ratings related to each of the immeasurables and assesses them on four different subscales: positive qualities toward self, positive qualities toward others, negative qualities toward self, and negative qualities toward others. Initial psychometric research with a college student sample found high internal consistency for each subscale and strong concurrent, discriminant and construct validity. The scale is quickly and easily administered in less than 5 min. The Self-Other Four Immeasurables (SOFI) scale is a tool that can be used for research on mindfulness, compassion, and positive psychology as well as to measure positive growth associated with regular mindfulness practice.