In 1902, he finished his studies in Iași, being awarded a silver medal, and left Romania for Paris, seeking to further develop his art skills.

In 1908, Ressu returned to Romania and became interested in social matters, contributing satirical drawings to several publications, including Furnica, Facla, and Adevărul.

In 1917, along with the painters Nicolae Dărăscu, Ștefan Dimitrescu, Iosif Iser, Marius Bunescu and the sculptors Dimitrie Paciurea, Cornel Medrea, Ion Jalea, and Oscar Han, he founded the Art of Romania association in Iași.

During these years, he further developed his style as a landscape painter, and frequently visited the countryside in summer to paint portraits of peasants working in the fields and views of villages.

In 1925, after a prolonged stay in the village of Ilovăț, Mehedinți County, Ressu finished one of his best-known paintings, Ploughmen Resting, currently housed in the Iași Museum of Art.