Welcome to the First International Workshop on Parallel and Distributed Algorithms for Decision Sciences (PDADS), 2021. The goal of this workshop is to create a forum for scientists, engineers and practitioners to share new results and collaborate on ideas at the intersection of parallel and distributed algorithms, decision sciences and combinatorial optimization. There is a growing recognition that a variety of science and engineering use-cases can benefit from parallel and distributed optimization frameworks with real-time decision-making capabilities. Especially in this age of ever-increasing powerful computing technologies, optimization-driven decision science problems that were otherwise considered computationally prohibitive for integration within scientific and engineering applications, especially those needing real-time decision-making capabilities, are now becoming possible. This workshop will focus on the theory, design, development and deployment of parallel and distributed algorithms for faster and more accurate solutions of different types of optimization problems that arise within the broader purview of the decision sciences.