Interest has been increasing in studying diatomaceous earth stemming from the challenges posed by the material’s presence in various engineering projects, such as the US 97 at Wickiup Junction project in Oregon. At Wickiup Junction, an overpass crossing was being built to replace the last at-grade rail crossing on US 97, and the presence of diatomaceous earth deposits caused significant and uneven settlement under the bridge abutment. Diatomaceous earth consists of fossilized remains of diatoms, which have a highly varied and interlocking shape, giving the impression of strength until the skeletons crush under excessive stress. The shape of these diatoms is unique to each of the estimated 20000 species, creating a highly varied material that may behave differently. The engineering properties of the diatomaceous earth are not well understood, particularly regarding methods to improve its shear strength and reduce its compressibility. This project explores the soil improvement of diatomaceous earth using cement modification. A series of geotechnical laboratory tests, including specific gravity, grain size distribution, direct shear test, and 1-D consolidation test, were performed on untreated and cement-modified diatomaceous earth. The cement content used in this research was 2.5%, 5%, and 15% by dry mass. The performance of cement-modified DE was tested at standard curing times of 1, 7 and 28 days. The findings reveal that DE had a significant strength increase with increasing cement content. For example, the 15% direct shear test had a 9% increase in friction angle and increased cohesion by 56.9 kPa. 1-D Consolidation testing shows a significant decrease in the compression index. For instance, the 15%, 28 day cured sample saw a reduction in the compression index (Cc) value of 69% and 77% reduction in swell index (Cs).