The microstructures formed in an Al<sub>2.7</sub>CrMnTiV high-entropy alloy are studied using a combination of atom probe tomography (APT), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and X-ray diffraction (XRD) as well as predictions from Thermo-Calc. In the as-cast state, the alloy consists of a body-centered cubic (bcc) matrix with micron-scale L1<sub>0</sub> lath-shaped precipitates, enriched in Al and Ti, that are predicted by Thermo-Calc. Additionally, coherent B2 cuboids on the order of 10 nm are formed, resembling the γ-γ' microstructure of Ni-based superalloys but in a BCC system. We study the precipitation-hardening behavior by solutionizing and aging the alloy, and measuring the mechanical properties after aging. After the solution heat treatment, the alloy is single phase BCC. The mechanical properties after aging are correlated with underlying microstructure and distribution of the ordered B2 nanoscale precipitates in the disordered BCC matrix.