This chapter discusses vowel patterns that involve indirect licensing. According to the hypothesized functional underpinnings for these systems, indirect licensing serves to reduce perceptual difficulty by causing a vowel quality to be produced both in a prominent position and an adjacent non-prominent position or sequence of non-prominent positions. Where a feature subject to licensing is restricted to a particular value or context, that material is expected to have the capacity to serve as marked. Because the licensing position is prominent, patterns are anticipated to occur where the shared vowel quality issues from this site. In patterns where the shared property originates in a vowel external to the licensing position, it is expected either that this vowel occurs in a position serving as another locus of strength in the word or that some independent factor prevents it from capitulating to the original value of the licensing position. This chapter concentrates on patterns with indirect licensing that do not also present identity licensing, that is, it excludes cases where a given vowel quality is produced in prominent position and a non-adjacent non-prominent position through feature duplication. Characteristics that may be indicative of an indirect licensing pattern are the existence of blocking effects and licensing-driven assimilation that can cause more than one vowel to undergo harmony.