In 1921, Mieli founded the Società italiana per lo studio delle questioni sessuali (Italian society for the study of sexual matters), an organisation to discuss sexuality and sexology. He also founded the journal Rassegna di Studi Sessuali (Sexual Studies Review). The journal published a range of topics on sex and sexuality, notably including the works of Magnus Hirschfeld. Hirschfield and Mieli had both been members of the organizing committee of the first Congress of Sexology, in Berlin, held earlier that year in 1921.
These activities formed part of Mieli's strategy to encourage public debate on sexual issues with a view to changing government policies on sexuality. He considered homosexuality a "completely natural fact, not something to cure but to be analysed with a high degree of objectivity", which Benadusi notes was an "absolute novelty".