In a complex and turbulent world, there is heightened interest in managing for resilience. However, resilience guides, particularly those used in the development field, often lack a theoretical grounding in complex adaptive systems. There is a demand for guidance on how to operationalize complexity in applications of resilience, such as resilience assessment and planning. This study synthesizes lessons from how twelve cases of social-ecological resilience practice are engaging with complexity. We assessed how each case engaged with complexity, according to a framework of six features of complex adaptive systems. The cases are situated in a diversity of contexts, that include rural villages in Tajikistan, a Swedish municipality, Australian catchment management authorities, a Canadian coastal fishery, and the Arctic council. Our results revealed two main ways of engaging with complexity: capturing and making sense of the complexity of a social-ecological system (system complexity) and embodying complexity into the participatory process (process complexity). Our comparison demonstrates that resilience practice provides a useful approach to address system complexity by, for example, conceptualizing social-ecological interactions, identifying interactions across scales, and assessing system dynamics. Strategies related to understanding the adaptive and emergent features of complex systems were less developed and widespread. The study also revealed a set of strategies to address process complexity, such as facilitating dialogue, building networks, and designing a flexible and iterative process, showing how complexity can be embedded into the resilience assessment process. The more participatory and embedded cases of resilience practice were stronger in these process-oriented strategies. The complexity framework we used and the identified practical strategies provide a theoretically-grounded resource for managers, decision-makers, and researchers on how to engage with complexity when applying resilience in a variety of contexts, including development and landscape management.