There is a controversial matter of debate as to the mechanism of the Cu⁰ catalyzed radical polymerization. Two models exist, one based upon ATRP whilst the other upon SET-LRP. Here we present new experimental results and insights into the nature of this polymerization. A good controlled/living polymerization was eventually obtained by Cu⁰&Cu^II/PMDETA-mediated radical polymerization. A comparative analysis shows that the mechanism behind this reaction lies between the competition and equilibrium results of SET-LRP and ATRP.