Abstract Despite the very positive – as measured by market surveys – attitude towards eco-innovations and sustainability in general, the actual market penetration of green products and practices generally falls behind the expectations. In this paper we argue that considering difficulty of engagement, as used in the Campbell Paradigm, is of critical importance when modeling diffusion of eco-innovations. Such a notion of difficulty possesses three desired properties: (i) parsimony – it is represented by a single value, (ii) interpretability – it can be regarded as an estimator of the otherwise complex notion of behavioral cost, and (iii) applicability – it can be easily measured through market surveys. In an extensive simulation and analytical study involving empirically measured difficulty and an agent-based model spanned on different social network structures, we show that innovation adoption may exhibit abrupt changes in market penetration as a result of even small changes in difficulty. The latter may be of particular interest to policy makers who have to make strategic decisions when introducing socially – but not necessarily individually – desired products and practices, like dynamic or green electricity tariffs.