The master's thesis in question analyses neoclassical theory and behavioral economics to determine their connection with advertising or market communication and find correlations with decision-making about advertising in companies. It was established that the aforementioned theories have very different views on investing in advertising. Neoclassical theory is not inclined to investments in advertising or market communication and sees it as an unnecessary cost. On the other hand, behavioral economy favours it and through its principles establishes its purpose and influence on individuals. The empirical research done by conducting interviews has shown that companies know their consumers, do research on them and adapt their investments in advertising according to their findings and as such act a lot more in line with behavioral economics than neoclassical theory. Companies use different strategies to influence consumers which also correspond with principles of behavioral economics. Overall, advertising costs in relation to financial planning of a company are often seen as an expense and not as an investment which is in agreement with the beliefs of neoclassical economists.