Social Movements in Times of Austerity. By Donatella della Porta. Cambridge: Polity, 2015. vii + 249 pp. Â£16.99 (pbk). ISBN 9780745688596. Networks of Outrage and Hope: Social Movements in the Internet Age. 2nd updated edition. By Manuel Castells. Cambridge: Polity, 2015. xix + 319 pp. Â£12.99 (pbk). ISBN 9780745695761. The first half of this decade has seen a tremendous wave of protest. The universally recognised spark of the Arab Spring was the self-immolation of Mohamed Bouazizi in December 2010. Since then weâ€™ve seen the Tunisian and Egyptian revolutions, protests turn to civil wars in Syria and Libya, the uprisings of the indignadas of Spain and the Occupiers of Wall Street (and passim), the Umbrella Movement of Hong Kong, a range of new movements in Brazil, Chile and Mexico, and much else besides. If we understand this â€˜movement of the streets and the squaresâ€™ as a coherent global wave of protest, what exactly does it signify? The two books under review offer interpretations of the most recent wave of protest that may help answer this most central question.