Frege, Contextuality and Compositionality

There are two principles which bear the name "Frege's principle:" the principle of compositionality, and the context principle. The aim of this contribution is to investigate whether this is justified: did Frege accept both principles at the same time, did he hold the one principle but not the other, or did he, at some moment, change his opinion? The conclusion is as follows. There is a development in Frege's position. In the period of Grundlagen he followed to a strict form of contextuality. He repeated contextuality in later writings, but became less strict. From 1914 on, pushed by the needs of research, he comes close to compositionality. But he could never make the final step toward compositionality for principled reasons, therefore he always would reject compositionality.