If engaging people in the effective altruism movement often allows them to do more good, then it follows that growing the effective altruism movement is one possible way to build capacity.
Examples of movement-building work include starting student groups, writing articles, and organizing social gatherings for people interested in effective altruism.
There is a relevant distinction between work that increases outside awareness of the movement and work that increases its favorability. Awareness and favorability are both limiting factors for movement growth, since a person would need to both know what the movement is and have a positive impression of it to want to become involved.
Ideally, movement-building work would increase both of these factors, but there is sometimes a trade-off between the two. For instance, one way that social movements often draw attention is by generating controversy. In addition, excessive movement growth may also decrease the effectiveness of the people within the movement.
Cotton-Barratt, Owen. 2015. How valuable is movement growth?