The rapid adoption of next-generation, direct, and single- molecule sequencing technologies has made DNA shearing a critically important step in library template preparation. DNA sonication is the preferred method to prepare high quality, random, and size-appropriate sequencing libraries, and also ideal to fractionate chromatin for epigenetics studies. Here we present optimized sonication methods and protocols using the Bioruptor® sonicator to make genomic DNA libraries for the Illumina®, HeliScopeTM, SOLIDT™ and 454 platforms.