Cohesion is an internal software attribute representing thedegree to which the components are bound together within a softwaremodule. Cohesion is considered to be a desirable goal in software development,leading to better values for external attributes such as maintainability,reusability, and reliability. Aspect-oriented software development(AOSD) is a new technique to support separation of concerns in softwaredevelopment. AOSD introduces a new kind of component called aspectwhich is like a class, also consisting of attributes (aspect instance variables)and those modules such as advice, introduction, pointcuts, andmethods. The cohesion for such an aspect is therefore mainly about howtightly the attributes and modules of aspects cohere. To test this hypothesis,cohesion measures for aspects are needed. In this paper, we proposean approach to assessing the aspect cohesion based on dependence analysis.To this end, we present various types of dependencies between attributesand/or modules in an aspect, and the aspect dependence graph(ADG) to explicitly represent these dependencies. Based on the ADG,we formally define some aspect cohesion measures. We also discuss theproperties of these dependencies, and according to these properties, weprove that these measures satisfy the properties that a good measureshould have.