The Province of Caltanissetta (Italian: Provincia di Caltanissetta; Sicilian: Pruvincia di Nissa) is a province in the southern part of Sicily, Italy. It contains 22 comuni (singular: comune), which are listed at Comuni of the Province of Caltanissetta. Its coat of arms is a red crest and two green leaf stems on top with a laurel leaf on the right and a crown in the middle. The River Salso is the main river of the province; it is 122 kilometres (76 mi) long and originates in the province of Palermo, and it flows into the Mediterranean in this province at the end of the Gulf of Gela.
As of 2010, it has a population of 271,729 inhabitants and an area of 2,128 sqkm, giving a population density of 130/sqkm. From 1406 to 1812 the province was owned by the Moncada family. The province was called "Nissa" by the Greeks, and Caltanissetta contains Gela, an highly important tourist destination.
The province extends to the central part of Sicily in the northwestern direction where the capital is located. The commune of Resuttano is found in an enclave of the province of Palermo near Caltanissetta between Monte Stretto and Portella del Vento. Another example in the same province is that of the two small localities of Cannetti and Corfidato, two frazioni of the comune of Enna, 15 km (9.3 mi) away, within the territory of the comune of Caltanissetta. The land extends to the Gela Plain and into the Gulf of Gela, where the main river of the province, the Salso, meets the Mediterranean.
Its population is 271,729. By population, the main communes are: