We observed highly enhanced fluorescence from a composite film consisting of a layer of significantly large Ag nano islands on which dye monomers were deposited with an intermediate molecular spacer in between. To clarify the mechanism of such a strong enhancement effect, we examined the influence of Ag islands shape, size, and spacer layer thickness. It was found that Ag island films with relatively flat shaped and considerably large discrete nanoparticles produced the highest enhancement that peaked at 10-20Å spacer thickness and tailed beyond-100Å away from the Ag island surface. The results suggest that the strong enhancement arises from an anomalously efficient emission from the induced dipoles in the Ag islands.