Due to increasing environmental regulations and requirements in the maritime sector, it is crucial that stakeholders not only understand the positive effects of green solutions from an ecological point of view but also see the positive synergies regarding operational and economic performance. Therefore, structures, processes, technologies, and methods that support green strategies fulfilling both economic and environmental objectives are desired by the industry and contribute to sustainable growth and development. This chapter introduces the concept of environmental sustainability in ports and explains how to incorporate environmental indicators into modeling and decision making. We present a framework encompassing different means for addressing environmental issues on various operational levels that are currently discussed in research and industry. Focusing on the area of planning and optimization, we give an overview of port operations and explain, by means of an example of berthing operations, how concepts and strategies, like slow steaming, can be considered in decision making.