|Abstract||In this work, the planning of unbalanced radial distribution systems is carried out. The objectives of this planning include total complex power unbalance, total line loss, average voltage drop, total voltage unbalance factor, and total neutral current. These objectives are minimized so as to obtain the optimal loading among the different phases, the optimal conductor sizes of the lines, the optimal locations, sizing of reactive, and the distributed energy sources in unbalanced radial distribution systems. The Differential Evolution (DE) is proposed as a solution strategy for the minimization of these objectives. A three-phase unbalanced load flow algorithm is developed for the calculation of these objectives. The proposed method is effectively tested on 19-, 25-, Indian 19-, and 34- bus unbalanced distribution systems. The results are compared to those obtained with some other metaheuristic algorithms, such as Cuckoo Search Algorithm (CSA), Particle Swarm Optimization (PSO), and Genetic Algorithm (GA). The comparison shows that DE provides better results than the other meta-heuristic algorithms.