  In July 2007, the blazar 3C 454.3 underwent a flare in the optical, reaching
R~13 on July 19. Then the optical flux decreased by one magnitude, being R~14
when the source was detected by the gamma-ray satellite AGILE, that observed
the source on July 24-30. At the same time, the Swift satellite performed a
series of snapshots. We can construct the simultaneous spectral energy
distribution using optical, UV, X-ray and gamma-ray data. These shows that an
increased gamma-ray flux is accompanied by a weaker optical/X-ray flux with
respect to the flare observed in the Spring 2005 by INTEGRAL and Swift. This
confirms earlier suggestions about the behaviour of the jet of 3C 454.3.
