Synthetic multicellular systems hold promise as models for understanding natural development of biofilms and higher organisms and as tools for engineering complex multi-component metabolic pathways and materials. However， such efforts require tools to adhere cells into defined morphologies and patterns， and these tools are currently lacking. Here， we report a?100% genetically encoded synthetic platform for modular cell-cell adhesion in Escherichia coli， which provides control over multicellular self-assembly. Adhesive selectivity is provided by a library of outer membrane-displayed nanobodies and antigens with orthogonal intra-library specificities， while affinity is?controlled by intrinsic adhesin affinity， competitive inhibition， and inducible expression. We demonstrate the resulting capabilities for quantitative rational design of well-defined morphologies and patterns through homophilic and heterophilic interactions， lattice-like self-assembly， phase separation， differential adhesion， and sequential layering. Compatible with synthetic biology standards， this adhesion toolbox will enable construction of high-level multicellular designs and shed light on the evolutionary transition to multicellularity.