The Triglav Glacier lies on the southeast edge of the Alps, in the Julian Alps below Mount Triglav, Slovenia’s highest peak. Its upper edge lies at 2,500 m. The glacier has been regularly measured, observed, and studied since 1946 by the Anton Melik Geographical Institute at ZRC SAZU. When measurements began it covered 14.4 ha, but today it covers less than half a hectare. The glacier no longer has all glacial features. Thus one may only speak of a glacier because of its past, when it clearly had the basic features of an alpine glacier. Analysis of the geomorphic forms of the Triglav Mountains allows reconstruction of past glaciation. Moraine deposits above the upper edge of Mount Triglav’s North Wall indicate the glacier’s extent during the Little Ice Age. When this ended in the nineteenth century, visits to the Triglav Mountains started increasing, and so there are many written and pictorial sources available from this time. The measurement period can be divided into four parts regarding glacial fluctuation. From 1946 to 1964 there was pronounced glacial retreat. The first geodetic measurement was in 1952. Based on these measurements, one can calculate the volume of the glacier. The second period, 1965 to 1982, saw stagnation in the glacier’s retreat. In most years the glacier was also covered with snow at the end of the melting period. The third period, 1983 to 2003, saw the fastest retreat of the glacier. Measurements were updated in the 1990s. In 1999 regular photogrammetric measurements began. That year we measured the thickness of the ice with ground-penetrating radar for the first time. In the last period after 2003, the glacier’s shrinkage has again slowed.