A self-report measure of changeable affect was developed, with a goal of identification of patterns of instability in mood. Scales measuring lability in anxiety, depression, anger, and hypomania, and labile shifts between anxiety and depression and hypomania and depression were constructed. These scales were then evaluated for internal consistency, retest reliability, score stability across samples, and for discriminant validity through assessment of association with measures of dysphoria and intensity of affect. The final versions of the scales are short scales that yield highly stable estimates of affect lability. It was noted that these scales are highly correlated in unselected students and it is believed that ongoing research with clinical populations will better allow for determination of the independence of these scales.