This chapter begins by analyzing the associations between recurrent brief depression (RBD), recurrent brief hypomania (RBM), and recurrent brief anxiety (RBA). All three recurrent brief psychiatric syndromes share an ultrarapid cycling pattern of mood symptoms. In association with major depressive episodes (MDEs), they clearly increase impairment and worsen treatment outcomes. Given this greater clinical severity of combined depression (CD), it is reasonable to hypothesize that bipolar II (BP-II) disorders combined with RBD also represent more severe clinical conditions than pure BP-II forms. The main goal of the chapter is to test this hypothesis by comparing diagnostic subgroups of mood disorders with and without RBD in a large number of validating clinical variables, including family history, course, personality, and comorbidity. The relationship of the two mood spectra with recurrent brief psychiatric syndromes (RBD, RBM, and RBA), with particular emphasis on RBD is focused in this chapter.