In trinitarian theology, the problematic place of the Holy Spirit in the taxonomy of the immanent Trinity (Father, Son and Holy Spirit) does not seem to correspond to what is revealed in the economy (Father, Holy Spirit and Son). Because of this pneumatological problem, some theologians have abandoned the traditional trinitarian taxonomy. This approach, however, does not provide a finally convincing answer that is consistent with both the biblical witness and the theological tradition. In this article, I argue that Hans Urs von Balthasar's theology of the trinitarian inversion and reversion does provide a convincing answer to the trinitarian taxonomy problem. After supporting my thesis by first referencing the traditional trinitarian taxonomy offered in Augustine's de Trinitate and then examining the possibility of abandoning the taxonomy given by Jürgen Moltmann and Leonardo Boff, I will offer von Balthasar's solution as the most compelling trinitarian taxonomy, especially in light of the ecumenical dialogue between the Roman Catholic and Eastern Orthodox churches.