Rare earth elements (REEs) are important for green and a large variety of high-tech technologies and are, therefore, in high demand. As a result, supply with REEs is likely to be disrupted (the degree of depends on the REE) in the near future. The 17 REEs are divided into heavy and light REEs. Other critical elements besides REEs, identified by the European Commission, are also becoming less easily available. Although there is no deficiency in the earth's crust of rare earth oxides, the economic accessibility is limited. The increased demand for REEs, the decreasing export from China, and geopolitical concerns on availability contributed to the (re)opening of mines in Australia and the USA and other mines are slow to follow. As a result, short supply of particularly terbium, dysprosium, praseodymium, and neodymium is expected to be problematic for at least the short term, also because they cannot be substituted. Recycling REEs from electronic waste would be a solution, but so far there are hardly any established REE recycling methods. Decreasing the dependency on REEs, for example, by identifying possible replacements or increasing their efficient use, represents another possibility. Urban mining of rare earth elements: Rare earth elements (REEs) are important resources for green and high-tech technologies. Export quotas, a price increase by a factor of ten, and geopolitical and sustainability concerns lead to the reopening of mines. The increased demand and decreased export will lead to a misbalance of four REEs (Nd, Tb, Dy, Pr) on the short term; therefore, as no alternatives are available yet, it is necessary to recycle these elements from electronic waste. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.