Chromatin assembly is a fundamentally important process that is essential for chromosome duplication subsequent to DNA replication. In addition, histone removal and incorporation take place constantly throughout the cell cycle in the course of DNA-utilizing processes, such as transcription, damage repair or recombination. In vitro, chromatin assembly requires the concerned action of histone chaperones and ATP-utilizing chromatin assembly factors. A novel, evolutionary conserved. ISWI-containing ATP-dependent chromatin assembly complex termed ToRC has been described. ToRC comprises ISWI, Toutatis and the transcriptional corepressor CtBP. In vivo studies have identified the Drosophila ATP-dependent chromatin-remodeling protein CHD1 as a key factor in the replication independent assembly of nucleosomes containing the variant histone H3.3. CHD1 functions within the network of partially redundant factors: mutations in individual chromatin assembly factors are viable, but combination of Chd1 mutations with mutations of other ATP-dependent chromatin assembly factors (acf1, dRsf1, tou) causes synthetic lethality. Thus, ATP-dependent molecular motor proteins, such as CHD1, function not only in remodeling of existing nucleosomes but also in de novo nucleosome assembly from DNA and histones.