This article analyses union strategies to enhance strike effectiveness in Italy and Spain in the Great Recession. These two countries have traditionally scored very highly in strike activity statistics due to an adversarial industrial relations framework. In both countries, unions have relied upon similar repertoires of industrial action. Even though they are often grouped under the same industrial relations cluster, there are some significant differences, particularly when it comes to union characteristics and power resources. An analysis of trade union strategies regarding industrial conflict and their attempts to enhance strike effectiveness shows how, in spite of similar challenges, the unions in Italy and Spain have followed different paths and fared differently in their attempt to enhance the effectiveness of industrial action.