Mutations and changes in a protein's environment are well known for their potential to induce misfolding and aggregation, including amyloid formation. Alternatively, such perturbations can trigger new interactions that lead to the polymerization of folded proteins. In contrast to aggregation, this process does not require misfolding and, to highlight this difference, we refer to it as agglomeration. This term encompasses the amorphous assembly of folded proteins as well as the polymerization in one, two, or three dimensions. We stress the remarkable potential of symmetric homo‐oligomers to agglomerate even by single surface point mutations, and we review the double‐edged nature of this potential: how aberrant assemblies resulting from agglomeration can lead to disease, but also how agglomeration can serve in cellular adaptation and be exploited for the rational design of novel biomaterials. The term agglomeration encompasses the amorphous assembly of folded proteins as well as their 1D, 2D, or 3D polymerization. Symmetric homo‐oligomers are prone to agglomerate, even through single surface point mutations. This Review summarizes how agglomeration can lead to aberrant assemblies and cause disease, how it can serve in cellular adaptation, and how it can be exploited for the rational design of novel biomaterials.