Abstract: In this chapter, we review the first 10 years of research in organic spintronic devices. This includes (1) organic spin valves (OSVs), where spin injection, transport, and manipulation have been demonstrated; (2) organic light-emitting diodes (OLEDs), where conductivity and electroluminescence have been strongly modulated by an external magnetic field ranging from 0.01 up to 100 mT; and (3) spin-polarized OLEDs (spin OLEDs), whose electroluminescence intensity depends on relative spin polarization (SP) of the ferromagnetic electrodes. In particular, we show in detail the role of the hyperfine interaction (HFI) on spin response in the devices based on conjugated polymers made of protonated H-hydrogen and deuterated D-hydrogen, having weaker HFI than that of protons. The possible mechanisms for the magnetic field effect (MFE) on OLEDs and spin OLEDs are also discussed.