Chromatin immunoprecipitation (ChIP) is a powerful method used for identifying genome-wide DNA-protein interactions in vivo. A large number of essential intracellular processes such as DNA replication, transcription regulation, chromatin stability, and others are all dependent on protein interactions with DNA. The DNA fragments enriched from the ChIP assay are analyzed by downstream applications, for example, microarray hybridization (ChIP-chip), quantitative PCR (ChIP-qPCR), or deep sequencing (ChIP-seq). This chapter presents a stepwise protocol for ChIP performed in hyperthermophilic archaea that we have successfully used in the hyperthermoacidophilic crenarchaeon Sulfolobus acidocaldarius.