We describe a long term project aimed at deriving information on the chemical evolution of the Galactic disk from a large sample of open clusters .
The main property of this project is that all clusters are analyzed in a homogeneous way , to guarantee the robustness of the ranking in age , distance and metallicity .
Special emphasis is devoted to the evolution of the earliest phases of the Galactic disk evolution , where clusters have superior reliability with respect to other types of evolution indicators .
The project is twofold : on the one hand we derive age , distance and reddening ( and indicative metallicity ) interpreting deep and accurate photometric data with stellar evolution models , and , on the other hand , we derive the chemical abundances from high-resolution spectroscopy .
Here we describe our overall goals and approaches , and report on the mid-term project status of the photometric part , with 16 clusters already studied , covering an age interval from 0.1 to 6 Gyr and Galactocentric distances from 6.6 to 21 kpc .
The importance of quantifying the theoretical uncertainties by deriving the cluster parameters with various sets of stellar models is emphasized .
Stellar evolution models assuming overshooting from convective regions appear to better reproduce the photometric properties of the cluster stars .

The examined clusters show a clear metallicity dependence on the Galactocentric distance and no dependence on age .
The tight relation between cluster age and magnitude difference between the main sequence turn off and the red clump is confirmed .