The first inhabitants of Alt-Klarenthal were workers and other employees of the mirror glass factory and the paper mill, which had been housed in the former Klarenthal monastery since 1706, as well as the administrator of the monastery estate. In 1755 there were twelve independent households. At that time, all structural remains from the monastery period, unless they had been used as foundations for new buildings, had been demolished.

In 1801, "Clarenthal" had 57 inhabitants. Between 1800 and 1820, the first houses were built on the left-hand side of the village street outside the former monastery ring. In 1730, a church was built over part of the former cloister, and a separate cemetery was used until 1869. A school, with its own building from 1881, existed until 1930. Around 1900, Alt-Klarenthal received a water pipe; ten years later, the town provided electric street lighting. According to the census of 01.12.1905, Alt-Klarenthal had 235 inhabitants.

A horticultural school was set up in the 1960s. The Mechtildshausen domain, run by the Wiesbadener Jugendwerkstatt (WJW), took over the former Klarenthal estate in 2004. The private integrated comprehensive school in Alt-Klarenthal was opened in 2008; it is run by Campus Klarenthal Gesellschaft and the main shareholder EVIM.