'Better to have a fence at the top of the cliff than a fleet of ambulances at the bottom'. Such is the call to early intervention: preventing legal problems from forming and escalating, rather than mopping up once the crisis has struck. The idea of early intervention has strong appeal: providing less intensive assistance early, before problems become more difficult and costly to resolve. But in the legal assistance sector, what and to whom does `early intervention` deliver? The impact of `early intervention` is based on two assumptions: (1) that priority clients groups are reached and assisted `early`; and (2) that the assistance provided will make a beneficial difference. This paper explores these assumptions in the context of the evidence-based priority given to assisting the most disadvantaged, and the need to do so within the scope and limited resources of the legal assistance sector.