We study the external and internal proliferation of country classifications in development policy. The number of classifications increased from four (1985) to 17 (2013) when the average in our sample of 111 developing countries exceeded three classifications per country. Based on historical overview and comparative case study for land-locked development countries and small-island development states (geographically defined classifications without overlap) we find that internal proliferation is associated with lacking a clear rationale, no definition of country characteristics, and possibly the direct involvement of developing countries in designing the category. External proliferation may reflect antinomic delegation, geopolitical and bureaucratic motives.