This paper deals mainldy with the history of phenological observations at the Royal Meteorological Institute of Belgium (RMIB) over the last 175 years. First, the setting of phenological observations in Europe in the 18th century is discussed. It is shown that Adolphe Quetelet was one of the 19th century trendsetters in these matters while Charles Morren can be credited for coining the word “phenology” in 1853. The possible interaction with the French “Bureau Central Météorologique” is highlighted not onldy for the similarity in their phenologic al instructions leaflets but also for the geographical and climatic neighbourhood of both countries. The 20th century’s phenological observations and network at the RMIB are described into more detail. Finally, a section is dedicated to the today’ use of phenological observations in the context of assessing long-term climatic va riability and Global Change detection.