He specialized in dependency grammar, topic–focus articulation and Common Czech.
His father was an attorney and a translator from Litomyšl of Jewish descent.
Sgall studied at Česká Třebová high school; however he was expelled in the 1942/43 academic year because of his Jewish father.
Most of Sgall's closest relatives were killed in the Auschwitz concentration camp.
His son is mathematician and computer scientist Jiří Sgall [cs] (* 1965).