Self-adaptive systems aim at autonomously achieving their objectives in a dynamic environment, adapting their behavior to different circumstances. We claim that appropriate software engineering methodologies are needed to define and to model the information necessary for a system to perform autonomous diagnosis and decision making at runtime.In this short paper we focus on conceptual modeling for the design of self-adaptive software. Our design framework adopts a goal-oriented approach to specify variability in system requirements, coping with some limits of current goal modeling approaches.