The Pacific crown-of-thorns starfish, Acanthaster sp. (CoTS), is a notorious boom-bust species whose extensive consumption of coral during periodic outbreaks have contributed to substantial habitat loss across coral reefs of the Indo-Pacific. However, the proximal causes of CoTS outbreaks remain elusive despite decades of research and investment into upscaling manual control (culling) efforts. Indeed, the Great Barrier Reef CoTS control program receives significant financial support (> $20 million yr-1) as a coral management tool, although understanding underlying outbreak dynamics could substantially improve its efficacy. Variation in predation pressure has been suggested as a local-scale mechanism constraining, or even preventing, CoTS outbreaks. However, CoTS predator-prey interactions are poorly resolved, especially for early life-history stages. In particular, the degree of predation vulnerability of juvenile CoTS that recruit to and develop in coral rubble habitat is largely uncharacterised but could represent a major bottleneck in the development of population outbreaks. Importantly, even small variations in mortality during early life-history stages are likely to disproportionately affect adult abundances. Thus, characterising the key ecological constraints dictating predation success will inform whether interactions with juvenile CoTS are of sufficient magnitude to have appreciable population consequences.Resolving the magnitude of predation mortality on juvenile CoTS is conditioned on working knowledge of the key predatory species co-occurring in their preferred rubble habitats. Chapter 2 evaluates the capacity of >100 rubble-dwelling species to consume early post-settlement CoTS juveniles. 26 novel CoTS predators were identified. However, predation success was highly variable among species and appeared to cluster based on either (1) infrequent interactions, (2) high frequency of partial predation events, or (3) consistent CoTS consumption. Most successful predators were decapod crustaceans (85%), with the partial predator archetype represented by species of the Portunidae and Xanthidae. A single species, the red decorator crab, Schizophrys aspera (Majidae), was noted to be a consistent CoTS predator that consumed juveniles in 89% of feeding trials.Chapter 3 expands on these initial findings by characterising CoTS predation risk across dimensions of predator-prey size, morphology and density for 5 key predatory decapods. CoTS predation risk declined with increasing CoTS size and decreasing predator sizes, but allometric scaling of predator risk differed among morphologically distinct predator species. Generalist portunid predators with weak, sharp claws were inefficient consumers (max consumption 2–4 CoTS d-1) that frequently caused injury and restricted feeding to CoTS 50%) increased the likelihood of subsequent mortality and temporarily reduced somatic growth, suggesting predator-induced injuries can indirectly impact juvenile CoTS success by altering demographic rates.Chapter 5 interrogates the potential for emergent multiple predator effects on juvenile CoTS mortality. Multi-predator interactions reduced CoTS consumption risk by up to 30% due to behaviourally mediated predator interference. However, emergent risk reduction was contingent on structurally simple rubble habitats with high alternative prey availability, which may have limited applicability to ecological conditions in natural rubble beds. Findings highlight that variation in CoTS mortality from predator-predator interactions is highly context-specific and appear to have limited influence in high complexity rubble habitats. Overall, this thesis provides in-depth understanding of key context-dependencies moderating predation on juvenile CoTS. Several key predators were identified, although results highlight distinct CoTS mortality and injury dynamics dependent on predator species and feeding type, predator-prey size ratios, habitat complexity and community composition. Variation in any, or several, of these ecological controls could alter the expected progression of juvenile CoTS cohorts with potential flow-on effects to adult CoTS outbreak development. These findings provide more complete understanding of the role of predators in regulating CoTS populations dynamics that may improve our ability to manage and predict future CoTS outbreaks.