Successful conservation of complex ecosystems, their function and associated services, requires deep understanding of their underlying dynamics and potential instabilities. While the study of ecological dynamics is a mature and diverse field, the lack of a general model that uses basic ecological parameters to predict system-level behaviour has allowed unresolved contradictions to persist. Here, we provide a general model of a mutualistic ecological community and show for the first time how the conditions for instability, the nature of ecological collapse, and potential early-warning signals, can be derived from the basic ecological parameters. We also resolve open questions concerning effects of interaction heterogeneity on both resilience and abundance, and discuss their potential trade-off in real systems. This framework provides a basis for rich investigations of ecological system dynamics, and can be generalised across many ecological contexts.