The objective of this work was to highlight the conceptions of force held by students aged 10-17 years old, in situations where animate and inanimate objects interact. In the proposed experimental situations, we varied parameters such as the motion and position of an object and the agent's effort. We asked questions about both inanimate and animate objects. Results show that pupils are able to use a small number of conceptions coherently, but that these are influenced by the context. For inanimate objects, conceptions develop gradually. Initially, force is regarded as a property of objects related to their weight and/or motion/position. With age, however, pupils begin to regard it as a process of interaction. For animates, conceptions evolve much more slowly, insofar as all pupils consider force to be a human property related to the result that is obtained and/or the agent's effort. (Contains 1 figure and 6 tables.) [Abstract is presented in both English and French.]