The resilience paradigm includes elements of Probabilistic Risk Assessment, but goes considerably further. First of all, the goal is to preserve (even if that entails graceful degradation at the initial stages) essential functionality and services at a system level. Second, besides making infrastructures less brittle to sustain stress or acute perturbations, the resilience paradigm aspires to design effective and efficient recovery strategies in advance, which entails reducing downtimes, and even learning from hazards to reduce fragility. Third, resilience inherently takes a system-level view of interconnected infrastructures, while applying both bottom-up (e.g., component-level fragility curves) and top-down (e.g., prioritization of sequential recovery post-hazard) measures. This chapter discusses opportunities and challenges, including emerging methods and tools, with specific resilience examples on individual and interconnected lifeline infrastructure networks at both the regional and urban scales.