Forest ecosystems, vital for biodiversity and climate regulation, are increasingly threatened by wildfires and climate change. This book chapter aims to provide a comprehensive analysis of methods used to measure forest resilience against these threats. This involves exploring both quantitative methodologies, focusing on specific ecosystem parameters, and qualitative ones that seek to understand contributing social and ecological factors. Earth Observation is emphasized as a critical tool for monitoring changes in forest health. The chapter underscores that forest resilience is multifaceted and cannot be described by a single metric; diverse approaches, including hydrological monitoring, machine learning, and decision support systems, are needed. Challenges in measuring resilience are discussed, such as dealing with heterogeneous data and the complexity of forest ecosystems. However, advances in technology provide significant opportunities for enhancing our understanding and ability to ensure the continued survival and prosperity of forest ecosystems.