The research of this doctoral dissertation involves two primary objects, namely the mental models of marketing managers and marketing performance. The main objectives of this dissertation were to explore and deepen previous theoretical knowledge about the role of managerial cognitions in the development and application of marketing capabilities, and to develop a conceptual model and empirically test the relationship between the mental models of marketing managers and marketing performance measured by the change in the brand strength. A mixed methods design was used in the empirical part of the dissertation. The data for the qualitative research were collected using the method of semi-structured in-depth interviews, and processed using the method of content analysis. In the quantitative research, the data were collected using a structured questionnaire, and analyzed using the methods of univariate (basic descriptive statistics of variables, t-test, ANOVA), bivariate (correlation analysis) and multivariate statistics (exploratory factor analysis, confirmatory composite analysis). Auxiliary hypotheses relating to combined marketing ambidexterity and a stronger emphasis on an ambidextrous capability were rejected. The result of testing the auxiliary hypothesis related to balanced marketing ambidexterity shows that marketing managers who place a stronger emphasis on marketing exploitation achieve a greater increase in the brand strength than those who strive for marketing exploitation and exploration in a balanced way. This, regardless of the assumed direction of the difference (empirical findings are mixed), provides support for the partial acceptance of the main hypothesis that there is a connection between mental models of marketing managers and brand strength. The scientific contribution of the paper is reflected in combining the three separate research streams of managerial cognition, marketing capabilities and ambidexterity. A new typology of mental models was proposed according to the relationship between marketing exploration and exploitation, and two new scales were developed to measure the focus on brand communication management and the focus on new product development, which partially filled the research gap identified in the literature. Practical implications include the possibility of judging managers' engagement in the marketing process through the prism of defined mental models and the potential contribution to the field of human resources management in the form of employee selection and education. In further research, it is recommended to consider other factors that can affect brand strength, to operationalize constructs differently and identify the strengths and weaknesses of particular mental models at different stages of the business development and brand and industry life cycles.