This article attempts to assess, in a quantitative way, how security/defense issues have been perceived in Belgium since the early 1970s among the mass public. This period has been characterized by breathtaking changes in the political and military world environment. How have Belgians reacted to these changes? The empirical evidence is based on a secondary analysis of public opinion data from the Eurobarometer series. The picture that emerges from the trend analysis is mixed. On the one hand, orientations towards the peace movement and arms limitations are more positive than before. On the other hand, many other indicators point to an increase in pro-defense orientations. Belgians are also overwhelmingly favorable to the creation of a collective organization for defense.