The theoretical framework of complexity is beginning to attract wider attention in research on the armed forces, and consequently the views of those who face complexity on the ground should be explored in more detail. Failure to do so risks complexity remaining only a top-level theory lacking adequate connection to practice. This article seeks to address this issue through analyzing the views of Finnish military officers. Data for the research were gathered using a deliberation and data collection method called a security café. A total of 74 people, most of them holding the rank of captain in the army or air force or lieutenant senior grade in the navy, attended the security café. The data used in this research were elicited from 47 idea rating sheets, evaluated during the security café, and include both quantitative and qualitative data. The article analyzes those data to address the following questions in relation to the theoretical framework of the article: What kind of perceptions of the complexity of the security environment do officers hold? What kind of practices do officers consider fit the presumed complexity of the security environment? ARTICLE HISTORY