Aspect-oriented software development allows the programmer to identify and treat separately concerns that, subsequently, can be woven to different target applications. For this, aspect-oriented languages like AspectJ and Hyper/J provide mechanisms for defining and composing such crosscutting concerns. An introduction is a mechanism for defining certain static crosscutting concerns, i.e., concerns that affect the type of the application they are woven to. This paper discusses the implementations of introductions in AspectJ and Hyper/J and reveals their limitations by presenting typical examples of static crosscutting code that cannot be handled adequately by them. To solve these deficiencies we will present the concept of parametric introduction, which are introductions that rely on parameters that are evaluated during weavetime.