As the most abundant protein in mammals, collagen provides essential structural support and connectivity to tissues while also mediating biochemical and mechanical signals that regulate cellular behavior. There is significant interest in developing peptide materials that mimic fibrillar collagen to emulate its role in the extracellular matrix, owing to the accessibility and versatility of synthetic peptides. However, using peptides to construct fibrillar structures poses a great challenge due to the limited approach to achieving one-dimensional aggregation of short peptides. This thesis describes a general strategy for designing peptides for the construction of triple-helical filaments. By leveraging the structural sensitivity of the collagen triple helix to steric perturbations, residues with collagen-disrupting steric bump sidechains were incorporated into the specific sites within the peptide sequences to prohibit the undesired configuration of collagen triple helices. Uniform self-assembly patterns are ensured by accommodating the steric bumps within the gaps between peptide termini, tethering staggered aligned peptide fragments into filaments and enabling endless propagation. As these filaments aggregated to various degrees, a diversity of higher-order structures emerged, including peptide gel networks, filament bundles, and nanocrystalline fibrils. The peptide hydrogel demonstrated notable high stiffness and unusual shear-thinning properties. Remarkably, the filament-forming specificity is achieved with only one or two side chain modifications on the peptide sequence, thus preserving the majority of the triple-helix available for further modification.Creating stable and short peptide mimics of the collagen triple helix is challenging, especially for collagen heterotrimers. Interstrand sidechain crosslinking offers a useful approach, though this strategy can suffer from destabilizing structural perturbations, sequence limitations, and synthetic complexity. This thesis demonstrates that the installation of terminal β-turn-mimicking linkers does not perturb collagen triple helix, as they share identical hydrogen bond geometry, allowing a seamless hybridization. These double-turn-containing peptides fold into highly stable, heterotrimeric, intramolecular triple helices, providing access to profoundly miniaturized collagen mimics. Intramolecular triple helix formation exhibits significantly accelerated folding kinetics. Comprehensive kinetic analysis reveals that the rate-limiting step of folding is distinct at low and high temperatures, affording unique insights into the collagen folding mechanism.