Microbial communities exhibit many advantages over monocultures due to division of labour, spatial organisation, and robustness to perturbations. Communities have unique catalytic activities and can use complex substrates by compartmentalization of pathways, and distribution of molecular burden. We now have the synthetic biology tools and approaches at hand that allow us to construct and control communities by engineering their communication, gene expression, and metabolic interactions. Controlling the behaviour of individual species within a community has consequences for the population dynamics. Computational models of metabolism and population dynamics, which can predict metabolic cross-feeding and infer population dynamics over time, help us to resolve complexity and systematically engineer communities . Combining model-based hypotheses with omic studies helped in the design and implementation of synthetic phototrophic microbial communities .