An equinus or plantarflexed positioning of the calcaneus relative to the tibia often results in shortening of the Achilles tendon, gastrocsoleus complex, or both. This may result in a number of patient symptoms including abnormal gait, pain with weight-bearing, toe walking, plantar forefoot callosities, and inability to properly fit into orthoses. When properly indicated, operative Achilles lengthening corrects fixed ankle equinus that exists with the knee flexed as well as extended. The ultimate goal is to improve ankle dorsiflexion, ideally to 10 degrees of ankle dorsiflexion past neutral with the knee flexed and 5 degrees with the knee fully extended. In this article, we discuss the clinical decision-making, various surgical techniques, and postoperative protocol of Achilles lengthening.