C. elegans striated muscle requires the serine/threonine kinase UNC-82 for proper organization of myosin filaments. Little is known about the targets of UNC-82 kinase, and the mechanism that regulates its activity has yet to be determined. Worms homozygous for unc-82(0) exhibit bright amorphous birefringent patches that contain the thick filament proteins myosin and paramyosin (Waterston et al., 1980; Hoppe et al., 2010). Our immunohistochemical analysis of unc-82 mutants that contain missense mutations in the kinase domain revealed distinctive ectopic birefringent paramyosin accumulations at the ends of muscle cells that are not found in the null mutant. Transgenes in which the missense unc-82(e1220) mutation is tagged with GFP/RFP show normal localization to the M-line in a wild-type background, but in the unc-82 null colocalize with birefringent accumulations at the ends of muscle cells. Driving expression of a heat-shock-inducible paramyosin::GFP in young adults showed that newly made paramyosin forms distinctive accumulations at the ends of cells in the missense mutant, consistent with the hypothesis that newly made paramyosin physically associates with UNC-82 protein. Dose-dependent synthetic lethality was observed between UNC-82 and mutations in paramyosin. Expression of UNC-82::GFP in the paramyosin mutant unc-15(e73) revealed that UNC-82 was recruited to the ectopic paramyosin-containing aggregates of this mutant, altering aggregate morphology and reducing motility and viability. UNC-82::GFP is recruited to paramyosin-containing aggregates formed in mutants that affect the M-line proteins UNC-89/obscurin, UNC-98/Zn-finger and UNC-96. We further explored physical interactions between UNC-82 and other M-line or thick-filament proteins by analyzing single and double mutant strains in which myosin, paramyosin or UNC-82 is abnormally localized within muscle cells, and determining which proteins are recruited to the aberrant structures. The phenotype of unc-82; unc-98 double mutants closely resembles that of unc-82 single mutants, suggesting that the two proteins act in a single pathway to organize paramyosin. The unc-89(su75);unc-82(e1220) double mutant is viable, exhibiting an enhanced phenotype compared to either mutant alone while the unc-89(su75);unc-82(0) double is not viable, indicating the two proteins are acting in parallel pathways. Our results suggest that UNC-82 physically interacts, either directly or indirectly, with paramyosin, but not myosin A, UNC-89 or the UNC-98/Zn finger protein. Our data are consistent with the model that UNC-82 kinase is epistatic to UNC-98 and is required for regulation, localization and incorporation of paramyosin into the thick filaments of the contractile apparatus.