This thesis adopts a complex systems approach to investigate the dynamic emergence of sustainable environmental governance and management systems in multiple contexts in Europe. Accelerating rates of environmental degradation across the world have called the legitimacy of previous environmental governance and management arrangements into question. Top-down, linear optimisation approaches have failed to account for the inherent complexity of social-ecological systems, upon which human society is entirely reliant for long-term survival. Systemic interdependence between ecological and human systems underscores the “wicked” nature of environmental problems, which are characterised by multi-dimensional values and competing interests among stakeholders and actors at multiple levels and across divergent spatial and temporal scales. Sustainability objectives therefore mandate the evolution of new environmental governance and management systems that are capable of engaging with complexity and dynamism. Employing a methodology based on comprehensive literature assessment, case studies and qualitative systems modelling methods, this thesis clearly identifies the structurally complex systems within which studied environmental governance and management arrangements took place. However, the degree to which these systems indicated the emergence of integrated and/or adaptive approaches, proposed by recent sustainability theories, was more uneven across governance levels and contexts. Key constraints related to the continued dominance of top-down institutional and regulatory frameworks, the availability of adequate inputs (primarily financial) for new approaches and initiatives, socio-cultural influences, and to the complexity and concomitant uncertainty of social-ecological system dynamics. Identified opportunities from across cases related to supra-national institutions, a shift of value preferences amongst stakeholders, and the perverse opportunities arising from chronic environmental degradation and/or acute social/ecological crises. Strategies enabling emergent governance and management approaches included strengthening the legitimacy of new actors, actively managing and integrating the perceptions of stakeholders, learning by doing and sharing, and recruiting and enabling active, hybridised leadership. Importantly, key constraints and opportunities remain largely out of reach for actors and stakeholders at lower levels. Feedback mechanisms by which bottom-up initiatives can influence higher level institutional development are lacking, poorly understood, or are dominated by long delays. These dynamics impede sustainability transitions.