The work highlights the general theoretical foundations for clarifying the essence of the concept of "costs", taking into account the current trends in the development of this category. The main classifications of expenses according to various characteristics are considered in detail. The regularities and functions of cost management, the importance of enterprise cost management forstimulating resource savings and justifying management decisions are revealed. The need to transform the cost management system at the enterprise under modern business conditions, in particular crisis phenomena in the economy, is substantiated; a systematic approach to the theoretical foundations of cost management as a factor in increasing the efficiency of the enterprise. The main methods of cost management are presented, their advantages and disadvantages are analyzed. It has been established that cost management can be defined as a system of principles and methods for the development and implementation of management decisions based on the use of objective economic laws.