Standard therapy for severe acute malnutrition (SAM) is home-based therapy with ready-to-use therapeutic food (RUTF) containing 25% milk. In an effort to lower the cost of RUTF and increase availability, some have suggested that a portion of milk be replaced with soy. This trial was designed to determine whether treating children with SAM with 10% milk RUTF containing soy would result in a similar recovery rate compared with the 25% milk RUTF. This was a randomized, double-blind, controlled, clinical, quasi-effectiveness trial of isoenergetic amounts of 2 locally produced RUTF to treat SAM in Malawi among children aged 6-59 mo. A total of 1874 children were enrolled. Children were assessed every fortnight and participated in the study until they clinically recovered or received 8 wk of treatment. The primary outcome was recovery (weight-for-height Z score > -2 and no edema). Secondary outcomes were rates of weight and height gain. Survival analysis was used to compare the recovery rates. Recovery among children receiving 25% milk RUTF was greater than children receiving 10% milk RUTF, 64% compared with 57% after 4 wk, and 84% compared with 81% after 8 wk (P < 0.001). Children receiving 25% milk RUTF also had higher rates of weight and height gain compared with children receiving 10% milk RUTF. Treating children with SAM with 10% milk RUTF is less effective compared with treatment with the standard 25% milk RUTF. These findings also emphasize that clinical evidence should be examined before recommending any changes to the formulation of RUTF.