
Solidaridad Internacional Antifascista

Solidaridad Internacional Antifascista (), SIA, was a humanitarian organisation that existed in the Second Spanish Republic. It was politically aligned with the anarcho-syndicalist movement composed of the CNT, FAI and other groups. One of its general secretaries was Lucía Sánchez Saornil, an anarcha-feminist activist.
It engaged in publicity and fundraising in an attempt to assist the refugee-packed Spanish Republic during the Spanish Civil War. It collaborated with the Mujeres Libres organisation to provide assistance to refugees and wounded soldiers.