Abstract
Embeddings of star-invariant subspaces K p θ of H p determined by an inner function θ are studied. Using a method of Aleksandrov, it is shown that the embedding into L p (μ) is compact whenever μ satisfies a certain vanishing condition with respect to the singular set of θ. Conversely, if the embedding is compact, and θ is a so-called one-component inner function, the measure is shown to satisfy a different vanishing condition.