Ambrosia artemisiifolia (Asteraceae) is an invasive annual plant introduced from North America to Europe over 100 years ago. This plant species is now widespread in numerous countries all over the world, causing damages to agricultural crops and human health. Ambrosia artemisiifolia is spreading as a weed in many field crops but is also able to invade a wide range of areas such as various human disturbed habitats or riverbanks (Figure 1). A considerable variability of the life history traits of A. artemisiifolia was previously observed among and within different populations (Fumanal et al., 2007). Since the success of colonization of some invasive plant species may result from their high phenotypic plasticity (Hassel et al., 2005), we addressed some specific questions : 1) are the invasive populations of A. artemisiifolia introduced in France locally adapted to their habitats or are they highly plastic according to their life history traits? 2) do detectable genotype*environment interactions exist? and 3) do their capacity of response to contrasted environments explain their invasive success?