Species introductions occur around the world both inadvertently and deliberately (typically for conservation, agriculture or fisheries). However, not all introduced species become established. Understanding the factors that affect the establishment success of introduced species will help us improve species introductions for biocontrol and conservation purposes. Here we argue that important generalist arthropod predators, the Coccinellini ladybirds (Coleoptera: Coccinellidae), are an ideal taxon for investigating the establishment process of introduced species. Coccinellini are introduced accidently via plant exports, as well as deliberately as biocontrol agents to reduce agricultural pests, and a few have become invasive species. Here, using work from invasive biology and biocontrol systems, we categorize the factors affecting the successful establishment of introduced species. These factors are 1) invasiveness of the species, 2) invasibility of the recipient ecosystem and 3) stochastic events that occur after the introduction. We review how factors such as diet and competition, dispersal ability, propagule population, disturbances and climate change can be studied within these three categories to better predict the establishment success of introduced ladybirds. Our review highlights that our current understanding of the differences between successful and unsuccessful species establishments is limited. To address this, we need direct comparisons of dispersal ability and both interspecific and intraspecific variation in ladybirds. We conclude that studies of ladybirds will help to develop theories that better characterize and predict establishment success and invasive potential.