In response to the World Commission on Environment and Development’s Brundtland Report (1987) and other documents that have brought the need to address environmental, economic, and social issues to the forefront of the awareness of the public, the Sustainable SITES Initiative was modeled after LEED certification and was formed to establish a rating system and comprehensive framework of guidelines for development. It is a collaborative effort between the ASLA, the Lady Bird Johnson Wildflower Center, and the United States Botanic Garden. In June 2015, the Green Building Certification, Inc. of the United States Green Building Council acquired SITES and will oversee future certifications. SITES was formed to address the need for a coordinated response between all landscape design professionals, and to work in addition to and synergistically with LEED certification. This study investigates the new sustainability rating system while exploring the professional marketplace and the design processes of three landscape architecture firms. The purpose of this study is to answer the question, “How do the design processes differ between SITES certified and noncertified urban open space projects in the Puget Sound area?”. There are currently 47 landscape projects across the United States that have been certified by the SITES pilot program rating system. This is an exploratory study that examines the processes of three landscape architecture firms, with two projects within each firm: one sustainably certified through SITES, one is not certified, for a total of six case studies. By analyzing and documenting the presence and nature of patterns, similarities and differences, this study aims to strengthen the objective of SITES certification for the purpose of recognition and to validate existing sustainable landscape architectural practices. This study pinpoints the components of sustainable landscape architectural and highlights landscape architecture’s commitment to sustainable development. Landscape architecture has a rich history of incorporating sustainable practices into their work. With this new rating system, landscape projects can gain recognition for sustainable practice through marketing projects as SITES certified, as the LEED certification program exemplifies. This study can also inform future collaborations with LEED certifications. SITES currently works synergistically with LEED certification on several components, but increased collaboration will be mutually beneficial. The SITES certification process is very involved and time-consuming, and with valuable feedback from Landscape Architects, expedited certification can be possible.