A t-butylphenylnitroxide (BPNO center dot) stable radical is attached to an electron donor-bridge-acceptor (D-B-A) system having well-defined distances between the components: MeOAn-6ANI-Ph(BPNO center dot)-NI, where MeOAn = p-methoxyaniline, 6ANI = 4-(N-piperidinyl)naphthalene-1,8-dicarboximide, Ph = phenyl, and NI = naphthalene-1,8:4,5-bis(dicarboximide). MeOAn-6ANI, BPNO center dot, and NI are attached to the 1, 3, and 5 positions of the Ph bridge, respectively. Time-resolved optical and EPR spectroscopy show that BPNO center dot influences the spin dynamics of the photogenerated triradical states (2,4)(MeOAn(+center dot)-6ANI-Ph(BPNO center dot)-NI-center dot), resulting in slower charge recombination within the triradical, as compared to the corresponding biradical lacking BPNO center dot. The observed spin-spin exchange interaction between the photogenerated radicals MeOAn(+center dot) and NI-center dot is not altered by the presence of BPNO center dot. However, the increased spin density on the bridge greatly increases radical pair (RP) intersystem crossing from the photogenerated singlet RP to the triplet RP. Rapid formation of the triplet RP makes it possible to observe a biexponential decay of the total RP population with components of tau = 740 ps (0.75) and 104 ns (0.25). Kinetic modeling shows that the faster decay rate is due to rapid establishment of an equilibrium between the triplet RP and the neutral triplet state resulting from charge recombination, whereas the slower rate monitors recombination of the singlet RP to ground state.