Thus between 1891 and 1895 the American School undertook investigations in the Theater, the Temple of Dionysos, and in the North Gymnasium, without however producing any final published report on these excavations.
The Archaeological Society of Athens played a crucial role in most of Tsountas' discoveries, for it financed his work, and encouraged its publication. It saw to the taking of photographs that are now documents of considerable value.
During the last years of the 19th century, the German Archaeological Institute sent several photographic missions to Eretria. The pictures they took constitute a second documentary group of great value.
In 1889, Konstantinos Kourouniotis excavated the temple of Apollo Daphnephoros and discovered one of the masterpieces of Greek sculpture, the group depicting Theseus and Antiope, now on exhibit in the Eretria Museum. Kourouniotis also found part of the fortification wall and the West Gate, the South Gymnasium, and the Baths near the harbor.
Alongside these official excavations, clandestine excavators looted the Macedonian tomb, which later became better known thanks to the objects that were stolen from it, and took the name of the Tomb of the Erotes.
In 1915, Nikolaos Pappadakis published a paper on the Sanctuary of Isis and the Egyptian divinities, which he had excavated over the preceding years.
Many scholars and foreign researchers have taken an interest in Eretria: one might cite in particular the great Austrian epigraphist Erich Ziebarth, the author of the volume of the Corpus Inscriptionum Graecarum devoted to Euboea, and more recently the historian William P. Wallace, the numismatist Olivier Picard, and John Boardman, a pioneer in studies on Eretrian pottery.