Tour operators are business entities that are located in the tourist markets, and which with their integration can contribute to the increase of the total tourist traffic, because they are the ones who enter into the contract on the sale of tourist package arrangements to the tourist. Sustainable development is extremely important for tourism, but also for the entire communities that live from it. It is responsible for taking care of the environment, society and the economy, so that natural resources are used efficiently and the balance that has been established is not threatened. In the last few years, people are more and more aware that they have to live ecologically and healthily, because it is precisely this way of living that enables survival, and when it is transferred to tourism, those destinations that take care of sustainable development are increasingly appreciated. Nowadays, the sustainable development of tourism is an important determinant that is essential for the development of tourism itself and for the further improvement of economic development. In order for tourism itself to be sustainable, all participants must be involved in its development, from generalist tour operators, travel agencies, to the local community, public administration and the tourists themselves who come to the destination. The subject is the business of generalist tour operators and the sustainable development of tourism, and the goals are theoretical and practical. It is theoretical to define and explain the business of generalist tour operators and to define the sustainable development of tourism and its principles and policies, and practical to show the role of generalist tour operators in the sustainable development of tourism.