  We review recent evidence for a clear association between accretion onto
supermassive black holes and star formation up to z~1 in the zCOSMOS survey.
Star formation rates (SFRs) are determined from the [OII] emission-line
strength and a correction for the AGN contribution. We find that SFRs of X-ray
selected AGN span a distribution of 1-100 solar masses per year and evolve in a
manner that is indistinguishable from that of massive, star-forming galaxies.
The close relationship between AGN activity and star formation is further
supported by an increase in the AGN fraction with bluer rest-frame colors
(U-V); we further illustrate how the location of AGNs in a color-magnitude
diagram can be misleading in luminosity-limited samples due to the dependence
of AGN activity on the stellar mass and the low mass-to-light ratios of blue
cloud galaxies. To conclude, our results support a co-evolutionary scenario up
to z~1 based on the constancy with redshift of the ratio between mass accretion
rate and SFR.
