Theories provide succinct explanations to events, phenomena and how they occur. The purpose of this chapter is to explore and compile theories in media, peace and conflict. To achieve this, the work identifies and reviews core propositions of relevant and prominent theories that have been used within the context of media, peace, conflict and national security researches. Theories that explain media, conflict and national security have applicability power in enhancing the understanding and usability of the term in a cross-disciplinary perspective. The chapter explains the possible applicability of each theory in enhancing the understanding and application of media, conflicts and peace from a cross-disciplinary perspective. Cross-disciplinary perspective has been the new trend in researches and this necessitates the need to understand how theories can be applied with practical guidelines. The chapter also reflects on the trend of applying an eclectic approaches and triangulation of theories with explanatory powers in media, peace and conflict studies within the confines of Nigeria and the West Africa. The work suggests how significant the various theories can enhance teaching, research and practice within the field of communication. The propositions of the theories identified in this chapter demonstrate their significance and relevance in particularly studying media content, audiences, journalists and media in relation to issues of peace, conflict and national security. Each theory is applied in communication based on its strength and suitability to the issue under review.