This book constitutes revised selected papers of the 8th International Workshop on Formal Aspects of Component Software, FACS 2011, held in Oslo, Norway in September 2011. The 18 full papers presented together with 3 invited talks were carefully reviewed and selected from 46 submissions. They cover the topics of formal models for software components and their interaction, design and verification methods for software components and services, formal methods and modeling languages for components and services, industrial or experience reports, and case studies, autonomic components and self-managed applications, models for QoS and other extra-functional properties (e.g., trust, compliance, security) of components and services, formal and rigorous approaches to software adaptation and self-adaptive systems, and components for real-time, safety-critical, secure, and/or embedded systems.