The KLOE experiment's major physics goal is to measure the R( ϵ′ ϵ), with a precision of 10 −4 , via both the traditional double ratio method and the kaons' quantum interferometry. The experiment has started taking data at DAfNE, the f-factory at the Frascati National Laboratory (LNF) of INFN in Italy, beginning in April 1999. Integrated luminosity exceeding 100 pb −1 (10 8 f's) are expected to be delivered for end 1999/early 2000. A description of the detector's design and of its performances is presented. At the moment of writing the experiment has collected its first collisions for an integrated luminosity of 220 nb −1 ; the peak luminosity reached has been of 2 × 10 30 cm −2 sec −1 .