Drawing on the literature on framing, we explore the emotional framing differences in radical and reformative NGOs over time. We analyse the sentiment of a sample of 5880 press releases issued by five NGOs positioned differently on the reformative-radical spectrum and examine how they address large companies. Our findings reveal an increasing polarisation of sentiment in these NGOs' framing, with individual NGOs gravitating towards ideal-type radical or reformative positions, respectively. In alignment with the differences in their framing, we observe differences in their approaches to cross-sector partnerships. Policymakers need to note the implications of the observed polarisation for the effectiveness and credibility of cross-sector partnerships and multi-stakeholder initiatives more generally, given the risk of co-optation (for reformative NGOs) as well as the risk of foregoing significant funding and governance opportunities (for radical NGOs).