Chromatin immunoprecipitation (ChIP) provides a versatile tool to investigate the in vivo location of DNA-binding proteins on genomic DNA. ChIP approaches are gaining significance in plants, in cases when entire genome sequences are available (e.g., Arabidopsis), for which several high-density oligo arrays have been or are being developed. Nevertheless, plant ChIP and ChIP-chip still present some technical challenges. Here, we describe general methods for ChIP and ChIP-chip, which have been successfully applied to maize and Arabidopsis.