Their preparation led to the 2 March 1884, launch of El Día, whose first issue boasted 4 pages and cost 5 cents; 900 copies were circulated that day.

Published in a small building near the former freight railway depot, the owners of the struggling daily persuaded a distinguished retired journalist, José María Mendía, to serve as its first director.

Soon earning renown for its timely coverage and for its outspoken editorials section on page 4, El Día was directed for most of the era between 1894 and 1952 by Hugo Stunz, who fended off periodic competition from the numerous upstart dailies which enjoyed a passing history in La Plata during the 20th century.

Inheriting a financially strapped company, Kraiselburd's staunch opposition to the era's military coups, and innovations such as special sections, helped recover El Día, whose circulation soon averaged over 70,000.

According to Columbia University's School of Journalism, which awarded both father and son the prestigious Moors Cabot Prize (in 1975, posthumously, to the former; in 2003 to the latter), the Kraiselburds maintained the independence of El Dia, which reported on disappearances and other issues that were covered up by most of the Argentine media during the Dirty War (1976–1983).