Dye-labeled samples of a chlorinated (21.8 wt % Cl), maleated polypropylene (CPO), and a dye-labeled sample of poly(ethylene-co-butene) (EBR28, with 28 wt % butene) were synthesized and characterized. The dye was a functional benzothioxanthene related to the commercial dye Hostasol Yellow 3G. These substances were introduced as tracers into blends of CPO with polypropylene (PP) and with EBR9 (9 wt % butene) as well as ternary blends of CPO + PP + EBR9. The morphology of the blends was examined by laser scanning confocal fluorescence microscopy. Control experiments at 5 wt % tracer showed that the dye-labeled CPO was fully miscible with its unlabeled precursor and that dye-labeled EBR28 was fully miscible with pure EBR9. The blend experiments showed that this particular CPO was much more miscible with EBR9 than with PP. Ternary blend experiments intended to mimic the composition of a thermoplastic polyolefin (TPO, with 25% EBR9 as the impact modifier) showed that the EBR formed micron size droplets in the PP matrix and that the CPO completely engulfed the EBR droplets to form a core-shell morphology. Center cross sections of these droplets showed the CPO layer to be uniform in thickness, with a sharp interface with the PP matrix. The inner interface, between the CPO and EBR, was noticeably broader, with a thickness on the order of 0.5 mum, indicating only weak segregation between these two components of the blend.