We give a criterion for q -valent analytic functions in the unit disk to belong to Q K , a Möbius-invariant space of functions analytic in the unit disk in the plane for a nondecreasing function K : [ 0 , ∞ ) → [ 0 , ∞ ) , and we show by an example that our condition is sharp. As corollaries, classical results on univalent functions, the Bloch space, BMOA, and Q p spaces are obtained.