Glavina was a member of the Istro-Romanian people (also known as "cici" and "vlahi") that in centuries past lived in a large section of the Karst (Carso) region from Castelnuovo (Rakalj) to Trieste. According to Ireneo della Croce's Historia sacra et profana antica et moderna of 1689, they came to Istria perhaps in the 1400s from Bucovina and Transylvania which are in today's Romania, thereby giving their name, Ciceria (now Cicarija), to that region.

During the XVIII and XIX centuries, the Istro-Romanian people lost much of their identity, both in territory and population, under the pressure of the Slovenians and Croatians. By the end of the XIX century, when Romanian scholars started becoming interested in this ethnic minority, their position was already critical for a number of reasons: 

• they lived in several remote areas fragmented in different communes,
• they had no juridical status,
• they had no schools in their own language, and
• their economic conditions were extremely poor.

In 1900, Andrea returned to Istria as a primary school teacher, first at Parenzo (Poreč), and then at Santa Domenica di Albona (Nedešćina) where he remained until 1918. At the same time, he was working for the advancement of his derelict people with a number of literary and administrative activities. He remained in contact with various Romanian scholars, in particular his professor at Blaj, A. Viciu, and Matteo Bartoli of Albona. In Bucharest he published in 1905 a Calendar, Lu Rumen din Istria, collected words, proverbs and folk stories of the cici to preserve their memory, and including a 10-page "Vocabular Istriano-Român" (PDF).

He fought tenaciously for the education of his people. There had been some precedents in this regard: a request to the Austrian administration for a Romanian school (in 1887 by Francesco Costantini), which was rejected. A Croatian school was opened in 1905, but that met with little success with the cici.

In Istria, Glavina started campaigning for the establishment of Romanian schools, and after many years of perseverance, at the end of World War I the authorities finally opened a school in the Romanian language in Sušnjevica. Andrea, as its director, named it after the Emperor Trajan for his historical association with Dacia (Romania).

The school proved very successful, having 180 pupils enrolled the first year (1919-20), with the tutoring done in Istro-Romanian, their native language. More teachers were called in, as well as didactic material from the Romanian Academy.

Unfortunately for the Istro-Romanian community, Andrea Glavina died prematurely in the hospital in Pola (now Pula) of tuberculosis on February 9, 1925 at age 43. Nonetheless, he is today remembered as being the greatest defender of the downtrodden Istro-Romanians, the most endangered ethnic minority in Europe.