Chromosome-wide regulation is of paramount importance for almost all aspects of biology and for human health. During sexual reproduction, regulated interactions between chromosomes are crucial for delivering the correct number of chromosomes to each gamete. Interactions between chromosomes are also essential for shuffling of genetic information and generation of genetic diversity. Our lab is studying a conserved protein complex that assembles between meiotic chromosomes in almost all eukaryotes — the synaptonemal complex (SC). The structure of the SC has intrigued biologists for decades: it is composed of regular striations that span the interface between perfectly parallel homologous chromosomes. The SC is essential for intimate associations between homologous chromosomes and it also regulates genetic exchanges. We combine a novel biophysical understanding of the SC, live microscopy innovations, and emerging genome editing technologies to observe chromosomes and to understand how the SC works.