In this study, we examined the role of the therapeutic alliance in complicated grief treatment (CGT), an efficacious psychotherapy for complicated grief. Using data from a previously reported randomized controlled trial, we explored whether the alliance–outcome relationship differs by treatment group among treatment completers assigned to either CGT (n = 35) or interpersonal psychotherapy (IPT) (n = 34). Early alliance (at week 4) was associated with a reduction in grief symptoms in CGT but not IPT. The difference in the alliance–outcome relationship was accounted for by goal/task items on the Working Alliance Inventory. The contribution of a positive alliance, particularly the agreement on goals and tasks, may be more significant in CGT, a highly structured treatment, than IPT in reducing symptoms of complicated grief.