This paper explores some meta-theoretical sources to cultural-historical activity theory by focusing on the concept of cultural mediation as it is construed in activity systems theory. Links to Charles S. Peirce's pragmaticism are identified and elaborated by comparison of the semiotic version of mediation with cultural mediation. The philosophical influence from Hegelian thought to both pragmaticism and activity systems theory is identified and elaborated with a focus on mediation. By a reinterpretation of C.S. Peirce's category the third-Thirdness, as "phaneroscopic mediation"-a partial overlap is found with cultural mediation. Although overlapping in the emphasis on mediation, activity theory, and pragmaticism also show some significant differences in scope and application.