Multiparty session types allow the definition of distributed processes with strong communication safety properties. A global type is a choreographic specification of the interactions between peers, which is then projected locally in each peer. Well-typed processes behave accordingly to the global protocol specification. Multiparty session types are however monolithic entities that are not amenable to modular extensions. Also, session types impose conservative requirements to prevent any race condition, which prohibit the uni- form application of extensions at different points in a protocol. In this paper, we describe a means to support modular extensions with aspectual session types, a static pointcut/advice mechanism at the session type level. To support the modular definition of crosscut- ting concerns, we augment the expressivity of session types to al- low harmless race conditions. We formally prove that well-formed aspectual session types entail communication safety. As a result, aspectual session types make multiparty session types more flexible, modular, and extensible.