Several recent studies have emphasised the importance of procedural justice in going beyond simplistic ‘NIMBY’ explanations for public protests against large-scale energy infrastructures such as wind farms and high voltage powerlines. These have drawn on calls for planning procedures to be more transparent, equitable and participatory, as advocated by sustainable development theory and legally enshrined in the Aarhus convention. This study seeks to extend the literature on procedural justice and the social acceptance of energy infrastructure by seeking to explain the determinants of different forms of behavioural engagement, arguing for important distinctions between diverse actions such as petition signing, making financial donations to protest groups and attending public meetings organized by development organisations. This was investigated in an empirical case study of a controversial proposal to construct a 60km high voltage overhead powerline through a rural area of South West England. 503 adult residents of the town of Nailsea, Somerset, completed a questionnaire survey in July/August 2009. A series of logistic regressions were conducted to establish the relative importance of procedural justice, as well as other variables (including socio-demographic characteristics, perceived impacts, trust and place attachment) in explaining behavioural engagement. Three specific forms of engagement behaviours were used as dependent variables in the analyses: attending meetings organized by the developer, signing a petition to object against the proposals and engaging with a local action group set up to protest against the powerline. These analyses showed that procedural justice was significant in explaining protest group support but not petition signing, supporting the proposition that distinctions should be made between different forms of public engagement. Conceptual and applied implications of the findings for the literature on procedural justice are discussed.