To achieve sustainable performance, a company needs to support its employees in their development, enhance their awareness of the changes needed and encourage them to take more responsibility for their own learning and growth. Coaching as one of the facilitating activities plays a significant role in triggering positive changes in employees’ behavior in the processes directed towards achieving work-related goals. Therefore, the number of companies that become interested in coaching is gradually growing in Latvia. However, there is a lot of uncertainty regarding the concept of coaching defining it in multiple ways; this leads to confusion in the understanding of its matter. Scholars are certain that coaching works and agree on the importance of assessing the impact of coaching interaction. Although they cannot reach consensus regarding the methodology appropriate for assessing the impact of coaching interaction.This issue is crucial also for companies which invest in coaching; they need to be sure that coaching really brings improvement in their performance. Therefore, the research conducted within this thesis aims to solve these research problems and elaborate a methodology for assessing the impact of coaching interactions on a company’s performance within its life cycle. To achieve this goal, the concept of coaching was investigated and defined based on what coaching is and is not, also considering the Baltic context. Types and forms of coaching, as well as favorable conditionsfor its promotion were determined and systemized for the needs of coaching in companies. An approach of choosing and adjusting the capacity of types and forms of coaching to the company’s needs and wants in development was worked out for creating the base of the methodology for assessing the impact of coaching interaction on a company’s performance. The methodology was elaborated and tested; that provides theoretical grounding and serves as a practical tool that enables to monitor the impact of coaching interaction on companies’ performance. The Doctoral Thesis has been written in English. The Doctoral Thesis comprises an introduction, four chapters, conclusions and recommendations, and list of references with 167 reference sources; it has been illustrated by 27 figures, 17 tables. The volume of the Thesis is 125 pages, not including 20 annexes.