Moving from the "What" (the content of programmes) to the "Why’s" (the objectives provided), this article shows how French political parties use election manifestos. We put forward three complementary hypotheses. First, we contend that uses of manifestos have diversified over time. Second, these uses vary in intensity from period to period. Third, both temporal variations are expected to reflect the changing rules of the political field. Overall, we show that considering the multiple transactions involved in the making of manifestos as an open question makes it possible to better account for how their content has evolved over time.