Whereas Georg Wenker had used postal questionnaires to compile his pioneering Sprachatlas des deutschen Reichs in 1888, Gilliéron employed a fieldworker, Edmond Edmont.

Between 1896 and 1900, Edmont conducted 700 interviews at 639 locations throughout the countryside of France, southern Belgium, western Switzerland, the Channel Islands, and the Aosta Valley and the Occitan Valleys of Piedmont in Italy, using a questionnaire of over 1,500 items devised and continually revised by Gilliéron.

Gilliéron's survey stimulated interest in dialect geography, and became the model for later works elsewhere.

Two of his students, Karl Jaberg and Jakob Jud, directed a survey of Italian dialects of Italy and southern Switzerland, published as the Sprach- und Sachatlas Italiens und der Südschweiz (1928–1940).

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