Adult multicellular eukaryotes consist of a multitude of different cell types varying in morphology, gene expression and function. However, it all begins with a single zygotic cell that, after several rounds of mitotic divisions, gives rise to emerging differentiating cell types. Although these cells share the same DNA, they develop distinct epigenetic and transcriptomic programs. In this project, by using single-cell profiling of the H3K27me3 and H3K27Ac histone marks—associated with repressed and active chromatin, respectively—we aim to uncover the establishment of these epigenetic programs. The divergence and progression of these programs can be represented as 'epigenetic landscapes,' a term coined by Conrad Waddington in 1957. We use Drosophila as it is a well-established model organism with thoroughly characterized embryogenesis, which can be staged within very narrow time frames, allowing for a higher temporal resolution in studying epigenetic processes.