A Schiff base type polymer containing phenanthrene and an aliphatic spacer in the main chain was prepared, and its photophysical behavior in diluted and concentrated solutions as well as in film form was studied by steady-state fluorescence spectroscopy. These data indicated that ground-state fluorescent phenanthrene aggregates were present in the films. Time-resolved measurements in diluted conditions showed biexponential decay implying in different microenvironments around the chromophore. Theoretical simulations predicted aggregation in pi-stack arrangement, and calculation of optical properties for small aggregates shows the introduction of new states at lower energies, in good agreement with the experimental results. Theoretical studies also forecast the possibility of domains with highly ordered morphology, which was confirmed by DSC measurements providing further support for the presence of the emitting aggregated form.