The aim of the paper is to examine whether conceptual relativism is a prerequi-site for conceptual engineering (and if so, then to what extent). In the first part of the paper, I explore and classify varieties of relativism to prepare a distinctive definition of conceptual relativism. In the second part I analyse conceptual relativism and I consequently propose two different readings of conceptual scheme: (i) conceptual scheme as a monolithic, timeless, and determinate systems of meanings, and (ii) conceptual scheme as (...) a system of relatively stable meanings, that is based on agreement and is open to change over time. In the third part of the paper, I show that of those two readings only the second reading of conceptual scheme fits into the practice of conceptual engineering. (shrink)