Kant’s philosophy very often serves as a standard of comparison when we try to characterize a philosophical position. One of the common features shared by many if not most philosophers belonging to the socalled Austrian tradition is allegedly their critical attitude toward Kant’s philosophy. Several commentators have even characterized Austrian philosophy as being anti-Kantian in witness whereof a long list of publications can be presented, starting with the New Anti-Kant by Bernard Bolzano’s pupil Franz Prˇíhonský (1850). There are, however, diﬀerent and even divergent ways of being anti-Kantian. This is not surprising if we take into account the sheer multiplicity of topics included in Kant’s philosophy. This multiplicity makes it quite unlikely that a single opposing view will take in all of them. Let us therefore focus on one single but central topic of Kant’s philosophy: the problem of the synthetic a priori. In this chapter I will try to show that the divergent Austrian ways of being anti-Kantian do not vanish even when we focus on this single topic. To illustrate this view, I will take as my examples Bernard Bolzano and Rudolf Carnap, who both belong – for diﬀerent reasons – to the so-called Austrian tradition in philosophy. Both are fully conversant with Kant’s work, and both have a critical attitude toward it and are in this sense anti-Kantian. This is also true when it comes to the question of the synthetic a priori: both refute strongly Kant’s treatment of the synthetic a priori. However, whereas Carnap denies synthetic sentences a priori altogether, Bolzano does not deny their existence but only the way in which Kant justiﬁes their truth. What is even more important is that Bolzano not only – contrary to Carnap – accepts Kant’s synthetic a priori, but even extends it to the realm of logic. In clear opposition to Kant and Carnap, who take all logical truths to be analytic, there are synthetic truths for Bolzano even in the area of logic. I will try to argue for this claim in the following sections.