Qualitative, quantitative and mixed methods are applied in security, political and other social sciences in order to conduct research and achieve or verify scientific knowledge. The aim of this paper is to explain the advantages of qualitative methods interview, focus group, observation or quantitative methods - survey, scales, etc. Besides, we will explain how to conduct research in security and political sciences by using some mixed methods. The mixed methods combine qualitative and quantitative methods in order to expand understanding of a certain problem. For example, mixed methods may combine interview and survey. Also, mixed method design may combine certain elements of research designs such as the research question, data collection or data analysis. Therefore, the mixed research designs, known as the third wave, are mostly applied in the research of security, political and other social phenomena.