Invasions by invasive non-native species (INNS) can have profound consequences for natural environments, impacting on biodiversity and the biophysical landscape in ways that can endanger other species, human wellbeing and infrastructure. The financial costs of dealing with established INNS populations can be extremely high. Biosecurity measures (simple procedures designed to reduce the risk of human activities spreading INNS to new areas) are being promoted in order to minimize these negative impacts and associated costs. This paper reports on research undertaken with stakeholder organisations that operate within UK natural environments. It aims to evaluate stakeholder perceptions of their role in INNS biosecurity practice in the UK, and the implications of this for INNS strategy more broadly. Semistructured interviews were undertaken with organisation representatives to explore current practices and communications about INNS and perceptions of barriers and opportunities to implement better biosecurity. Whilst participants generally agreed on the need for biosecurity, there were variations among participants in levels of knowledge about INNS (related to background) and the capacity of organisations to engage in biosecurity practices (related to organisational size). Critical barriers to biosecurity were identified as costs, lack of clear guidance, difficulties changing attitudes and implementing collective responsibility, and reactionary versus precautionary approaches. As a result, partnership working on INNS is difficult and action tends to focus on individual species perceived as the most threatening to a particular organisations' interests. In this way, action on INNS biosecurity faces the kinds of barriers that are common to many environmental problems where individuals/organisations prioritise self-interest despite the potential to obtain greater benefits if collective action could be achieved.