Purpose: This chapter seeks to explain why Spanish companies are so active in Global Compact (GC) initiative, while their external environment is worse than other European countries. From 2010 onwards, Spain ranks first in business participants in Global Compact initiative, ahead of European countries with higher levels of transparency and higher quality of governance. Design/methodology/approach: In this chapter we relate the Spanish evolution of GC signatories and external uncertainty (measured by Worldwide Governance Indicators and Corruption Perception Index); pointing out two theoretical approaches: Institutional and Social Identity Theories. Findings: Economic perspective is not sufficient to explain the companies' adhesion to the GC initiative. In this chapter we explain the companies' behaviour regarding to the CSR activities from a social perspective. Practical Implications: This chapter provides a response to understand the active behaviour of Spanish companies regarding to GC initiative. Originality/value of chapter: This is the first study that analyses the relationship between the GC evolution in a country and its external uncertainty. Moreover it contributes to the CSR field by providing two theoretical approaches that offer complementary explanation and advance our knowledge about the GC motivations