Context : The accretion process has a central role in the formation of stars and planets .

Aims : We aim at characterizing the accretion properties of several hundred members of the star-forming cluster NGC 2264 ( 3 Myr ) .

Methods : We performed a deep ugri mapping as well as a simultaneous u -band+ r -band monitoring of the star-forming region with CFHT/MegaCam in order to directly probe the accretion process onto the star from UV excess measurements .
Photometric properties and stellar parameters are determined homogeneously for about 750 monitored young objects , spanning the mass range \sim 0.1–2 M _ { \odot } .
About 40 % of the sample are classical ( accreting ) T Tauri stars , based on various diagnostics ( H _ { \alpha } , UV and IR excesses ) .
The remaining non-accreting members define the ( photospheric + chromospheric ) reference UV emission level over which flux excess is detected and measured .

Results : We revise the membership status of cluster members based on UV accretion signatures , and report a new population of 50 CTTS candidates .
A large range of UV excess is measured for the CTTS population , varying from a few times 0.1 to \sim 3 mag .
We convert these values to accretion luminosities and accretion rates , via a phenomenological description of the accretion shock emission .
We thus obtain mass accretion rates ranging from a few 10 ^ { -10 } to \sim 10 ^ { -7 } M _ { \odot } /yr .
Taking into account a mass-dependent detection threshold for weakly accreting objects , we find a > 6 \sigma correlation between mass accretion rate and stellar mass .
A power-law fit , properly accounting for censored data ( upper limits ) , yields \dot { M } _ { acc } \propto M _ { * } ^ { 1.4 \pm 0.3 } .
At any given stellar mass , we find a large spread of accretion rates , extending over about 2 orders of magnitude .
The monitoring of the UV excess on a timescale of a couple of weeks indicates that its variability typically amounts to 0.5 dex , i.e. , much smaller than the observed spread in accretion rates .
We suggest that a non-negligible age spread across the star-forming region may effectively contribute to the observed spread in accretion rates at a given mass .
In addition , different accretion mechanisms ( like , e.g. , short-lived accretion bursts vs. more stable funnel-flow accretion ) may be associated to different \dot { M } _ { acc } regimes .

Conclusions : A huge variety of accretion properties is observed for young stellar objects in the NGC 2264 cluster .
While a definite correlation seems to hold between mass accretion rate and stellar mass over the mass range probed here , the origin of the large intrinsic spread observed in mass accretion rates at any given mass remains to be explored .