The Scientific Workflow Integrity with Pegasus project will strengthen cybersecurity controls in the Pegasus Workflow Management System in order to provide assurances with respect to the integrity of computational scientific methods. These strengthened controls will enhance both Pegasus’ handling of science data and its orchestration of software-defined networks and infrastructure. The result will be increased trust in computational science and increased assurance in our ability to reproduce the science by allowing scientists to validate that data has not been changed since a workflow completed and that the results from multiple workflows are consistent. The focus on Pegasus is due to its popularity in the scientific community as a method of computation and data management automation. For example, LIGO, the NSF-funded gravitational-wave physics project, recently used the Pegasus Workflow Management System to structure and execute the analyses that confirmed and quantified its historic detection of a gravitational wave, confirming the prediction made by Einstein 100 years ago. The proposed project has established collaborations with LIGO and additional key NSF infrastructure providers and science projects to ensure broadly applied results.