Other communities bordering on Waldbrunn are, clockwise from the north, Mengerskirchen, Merenberg, Beselich, Hadamar, Elbtal, Dornburg and Neunkirchen.

The community of Waldbrunn is largely coëxtensive with the former parish and tithing area of Lahr, one of four that once belonged to the Amt of Ellar.

The three other parishes were the tithing areas of Frickhofen, Elsoff and Niederzeuzheim (known collectively as the Vier Centen).

The oldest trace of man in what is now the community is an urnfield grave from the Bronze Age near Fussingen.

In Frankish times, the Amt of Ellar with its four tithing areas belonged to the Niederlahngau under the Counts of Diez.

In 1401, Gerhard Kelner appears as the first Keller (a kind of estate manager) of the County of Katzenelnbogen in Ellar.

From 1491 comes the oldest preserved print of the Ellar court's seal, which later yielded today's civic coat of arms.

In 1609, Greden, mentioned as “Rörichs Johanns Weib” (that is to say, his “woman”, although the word is cognate with the English “wife”) from Ellar, was put to death in Hadamar after having been found guilty of being a witch.

The villages in the Amt of Ellar became Catholic again in 1630, whereupon Prince Johann Ludwig of Nassau-Hadamar authorized the Jesuits.

The upheaval brought about by the Thirty Years' War led to considerable losses in the surrounding centres.

Besides plunderings by soldiers moving through the area, the people also suffered food shortages and many outbreaks of illness.

In 1736 came an uprising in the villages of Dillhausen, Dorchheim, Dorndorf, Ellar, Fussingen, Frickhofen, Hausen, Hintermeilingen, Mühlbach, Lahr, Langendernbach, Probbach, Waldernbach, Wilsenroth and Winkels against the war tax that Prince Christian of Nassau-Dillenburg had imposed on them.

In the latest elections in March 2020 the incumbent mayor Peter Blum (independent) was re-elected.

The arms show on the sinister side (left from the armsbearer's point of view; right from the viewer's) the lion of the House of Nassau (gold on blue), and on the dexter side (right from the armsbearer's point of view; left from the viewer's) the lion of the County of Katzenelnbogen (red on gold).

In Hintermeilingen on 16 July 2006, the Hintermeilinger Geschichts- und Museumsverein (“History and Museum Club”) was founded.

Ellar belongs to the feeder area for the St. Blasius Mittelpunktschule (roughly “comprehensive school”) in Frickhofen.