Regional Conservation Partnership Program Improvement Act of 2018 This bill amends the Food Security Act of 1985 to make several modifications to the Department of Agriculture (USDA) Regional Conservation Partnership Program (RCPP). (The RCPP currently operates through several USDA conservation programs to provide funding for partners to join in efforts with producers to increase the restoration and sustainable use of soil, water, wildlife, and related natural resources on regional or watershed scales.) The bill modifies the program to: require the RCPP to be operated as a separate program rather than through several existing USDA conservation programs, expand the purposes of the program, expand the authority of project partners to define the scope of the activities that will help achieve conservation benefits, require USDA to set timelines for entering into contracts and providing funding, require USDA to establish program coordinators in each state, modify the requirements for allocating funding for the program, modify the application process and requirements for program contracts, authorize USDA to award grants to partners to directly operate conservation projects, authorize USDA to advance funding to partners for project development and outreach activities, and establish reporting requirements for partners regarding the progress made toward addressing natural resource concerns and related outcomes of the projects.