Quantum sensors capitalize on the strong sensitivity of quantum systems to external disturbances to measure various physical phenomena with extreme precision. Quantum sensing is a rapidly emerging field with many applications, including detecting gravitational and magnetic fields, biological measurement, imaging, etc. The full potential of quantum sensing is realized by using a distributed network of quantum sensors to estimate physical phenomena; in particular, when a network of quantum sensors allows the sensors to be in an entangled (correlated) state, its precision is further improved. There has been recent work using multiple quantum sensors, but the use of a distributed network of quantum sensors working collaboratively to estimate complex physical phenomena, as in many classical sensor network applications, has remained largely unexplored. This proposal seeks to fill this gap and investigate many scientific challenges that arise in developing efficient sensing protocols for a quantum sensor network (QSN). In addition, the project helps develop the workforce in this emerging quantum sensing and communication field by designing and offering educational programs targeting a wide variety of students ranging from those in high school to those in graduate school and beyond. The goal of this project is to tackle the main challenges and problems that arise in building QSNs. The research work consists of the following thrusts: (i) Initial State and Measurement Optimization.