Building effective altruism refers to the family of interventions aimed at growing, shaping or otherwise improving effective altruism as an intellectual community.
Examples of movement building 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, which tends to decrease favorability.
In addition, excessive movement growth may also decrease the effectiveness of the people within the movement.