Experimental design deals with the methods for planning and conducting valid experiments. Designing field experiments requires a set of correct decisions, such as the selection of treatments, the number of replicates, the size and shape of plots, and the techniques for allocating treatments to experimental units, among others. Although there cannot be a unique and consistent protocol across all disciplines in agriculture, some general hints are given in this chapter. In particular, the main layouts for the allocation of the experimental treatments (e.g., completely randomized, complete blocks, Latin square, split-plot, and strip-plot) are presented, and their advantages and limitations are discussed.