Aspect composition is a challenging and multi-faceted issue, generally under-supported by current AOP languages and frameworks. This paper presents the composition support provided in Reflex, a versatile kernel for multi-language AOP in Java. The core of Reflex is based on a model of partial reflection whose central abstractions are links: bindings between a (point)cut and an action. Reflex supports the definition of aspect languages through the mapping of aspects to links. We overview the wide range of features for link composition in Reflex—which includes extensible operators for ordering and nesting of links, and control over the visibility of changes made by structural aspects—, illustrating how they can be used to implement various scenarios of aspect composition.