Chromatin remodeling during development is a dynamic process involving structural and histone modifications, with ATP-dependent enzymes playing a key role. These enzymes are essential for establishing and maintaining pluripotent and multipotent states in cells. Chromatin remodeling is crucial for packaging DNA into a nucleus, enabling replication and transcription in stable, tissue-specific patterns. The basic unit of chromatin is the nucleosome, which compacts DNA about sevenfold. However, most chromatin is present in highly compacted structures that allow for the induction of developmental programs. Three processes control chromatin assembly and regulation: DNA methylation, histone modifications, and ATP-dependent chromatin remodeling. ATP-dependent remodeling is crucial for both the assembly and dissolution of chromatin structures. About 30 genes encode the ATPase subunits of these complexes in mammals, with most being genetically non-redundant. These enzymes have similar activities in vitro but require better assays to determine their biological functions. Genome-wide analysis techniques, such as ChIP–SAGE and ChIP–Seq, have improved our understanding of chromatin regulation. These approaches, combined with RNAi screening and genetic methods, are revealing the role of ATP-dependent remodelers in development, particularly in stem cells. The review highlights the key developmental roles of four classes of ATP-dependent chromatin-remodelling enzymes in Drosophila and mice, showing their importance in establishing and maintaining pluripotency in embryonic stem cells. ATP-dependent chromatin-remodelling families, such as SWI/SNF, ISWI, CHD, and INO80, have evolved to accommodate changes in chromatin regulation during vertebrate evolution. These complexes have diverse functions, with some being cell-type specific and others involved in developmental-stage-specific processes. The SWI/SNF family, for example, has evolved to accommodate changes in chromatin regulation during the transition from unicellular eukaryotes to vertebrates. The BAP complex is essential for the proper expression of homeotic genes in Drosophila, determining body segmental identity. In mammals, BAF complexes have similar roles in development, with different subunit compositions during development. The esBAF complex is crucial for maintaining the self-renewal and pluripotency of mouse embryonic stem cells. The TIP60-p400 complex is also required for maintaining the self-renewal potential and pluripotency of ESCs. CHD complexes, including CHD1, play a role in transcriptional activation and gene regulation. The INO80 family is involved in transcriptional regulation and DNA damage repair. The study of these complexes has revealed their non-redundant roles in pluripotency and development, with each complex having a specialized, programmatic function. The review also highlights the importance of combinatorial assembly in generating diverse gene-expression patterns and the need for further research to understand the mechanisms by which these complexes function.Chromatin remodeling during development is a dynamic process involving structural and histone modifications, with ATP-dependent enzymes playing a key role. These enzymes are essential for establishing and maintaining pluripotent and multipotent states in cells. Chromatin remodeling is crucial for packaging DNA into a nucleus, enabling replication and transcription in stable, tissue-specific patterns. The basic unit of chromatin is the nucleosome, which compacts DNA about sevenfold. However, most chromatin is present in highly compacted structures that allow for the induction of developmental programs. Three processes control chromatin assembly and regulation: DNA methylation, histone modifications, and ATP-dependent chromatin remodeling. ATP-dependent remodeling is crucial for both the assembly and dissolution of chromatin structures. About 30 genes encode the ATPase subunits of these complexes in mammals, with most being genetically non-redundant. These enzymes have similar activities in vitro but require better assays to determine their biological functions. Genome-wide analysis techniques, such as ChIP–SAGE and ChIP–Seq, have improved our understanding of chromatin regulation. These approaches, combined with RNAi screening and genetic methods, are revealing the role of ATP-dependent remodelers in development, particularly in stem cells. The review highlights the key developmental roles of four classes of ATP-dependent chromatin-remodelling enzymes in Drosophila and mice, showing their importance in establishing and maintaining pluripotency in embryonic stem cells. ATP-dependent chromatin-remodelling families, such as SWI/SNF, ISWI, CHD, and INO80, have evolved to accommodate changes in chromatin regulation during vertebrate evolution. These complexes have diverse functions, with some being cell-type specific and others involved in developmental-stage-specific processes. The SWI/SNF family, for example, has evolved to accommodate changes in chromatin regulation during the transition from unicellular eukaryotes to vertebrates. The BAP complex is essential for the proper expression of homeotic genes in Drosophila, determining body segmental identity. In mammals, BAF complexes have similar roles in development, with different subunit compositions during development. The esBAF complex is crucial for maintaining the self-renewal and pluripotency of mouse embryonic stem cells. The TIP60-p400 complex is also required for maintaining the self-renewal potential and pluripotency of ESCs. CHD complexes, including CHD1, play a role in transcriptional activation and gene regulation. The INO80 family is involved in transcriptional regulation and DNA damage repair. The study of these complexes has revealed their non-redundant roles in pluripotency and development, with each complex having a specialized, programmatic function. The review also highlights the importance of combinatorial assembly in generating diverse gene-expression patterns and the need for further research to understand the mechanisms by which these complexes function.