Using magneto-optical Kerr effect, SQUID magnetometry and magnetic circular dichroism spectroscopy, ferromagnetism was found below 4.5K in iron phthalocyanine thin films grown by molecular beam epitaxy. The stacking of the molecules can be controlled via deposition temperature and substrate choice. The molecules self-assemble such that quasi one-dimensional iron chains form. The chains are limited in length by the grain size or film thickness which is manipulated using judicious growth methods. Magnetic hysteresis loops show distinct features in the saturation magnetization and susceptibility that depend on the thin film structure and/or substrate. We find two regimes for the magnetic behavior: below temperatures of ∼ 25K, intra-chain interactions couple the Fe ions and produce non-traditional paramagnetic behavior, while at low temperatures below ∼ 4.5K interactions between the one-dimensional chains produce hysteresis, magnetic order, and slow magnetization dynamics.