Bridge deck cracking is a huge problem in the United States, and various agencies have sponsored research endeavoring to determine the underlying problems. A number of causes have been identified, including thermal movement, plastic shrinkage, and early age settlement, as well as a number of other issues. Polymer fibers are a possible solution to many of the causes of bridge deck cracking: they have been shown to help early age properties like shrinkage and movement, and as a bonus, fibers improve post-cracking behavior. More understanding of the benefits and uses of polymer fibers in concrete is needed. This study researched the properties of four polymer fibers; two of the fibers were macrofibers, and two were microfibers. Each fiber was tested at several dosage rates to identify optimum dosage levels. Early age shrinkage, long term shrinkage, compressive strength, and tensile strength were investigated. Macrofibers and microfibers were found to have different impacts on concrete behavior, with different optimal dosage rates. Microfibers greatly dried out the concrete mixture, hindering workability. However, the microfibers substantially reduced plastic shrinkage and improved concrete strength at early age. Macrofibers, while not hindering workability, did not provide benefits as great as the microfibers to the concrete strength.