Digital methods have the potential to strengthen social movement studies because digital trace data have the affordances necessary to record aspects of social life related to several problems of particular prominence in social movement research, namely: (i) group formation, (ii) unexpected and consequential events, (iii) mobilization cycles, (iv) persistence of activism, and (v) within-movement interaction and negotiation. Yet, suitable data for studying these phenomena have been rare. The reason is the informal nature of most social movements, making movement populations hard to delimit and reach, as well as the difficulty of predicting mobilization so that data can be collected before, during, and after a protest event making movements' populations hard to predict: in sum, the problem of ephemeral populations. Furthermore, because many movements do not keep systematically organized records of meeting minutes and the like, the level of micro-negotiations and internal cultures are difficult to measure. In these regards, digital trace data and methods offer promising new empirical tools.