前古典期即玛雅文化形成期，年代约当公元前2500～公元250年。在尤卡坦半岛中央佩滕盆地及其周围山谷已出现定居的农业生活，玉米和豆类是主要的作物；由土台、祭坛等组成的早期祭祀中心也已建立，此后出现国家萌芽，并出现象形文字。
The first complex civilization to develop in Mesoamerica were the Olmec, who inhabited the gulf coast region of Veracruz throughout the Preclassic period. The main sites of the Olmec include San Lorenzo Tenochtitlán, La Venta, and Tres Zapotes. Although specific dates vary, these sites were occupied from roughly 1200 to 400 BC. Remains of other early cultures interacting with the Olmec have been found at Takalik Abaj, Izapa, and Teopantecuanitlan, and as far south as in Honduras. Research in the Pacific Lowlands of Chiapas and Guatemala suggest that Izapa and the Monte Alto Culture may have preceded the Olmec. Radiocarbon samples associated with various sculptures found at the Late Preclassic site of Izapa suggest a date of between 1800 and 1500 BC.
The Middle and Late Preclassic witnessed the rise of the Maya in the southern Maya highlands and lowlands and at a few sites in the northern Maya lowlands. The earliest Maya sites coalesced after 1000 BC, and include Nakbe, El Mirador, and Cerros. Middle to Late Preclassic Maya sites include Kaminaljuyú, Cival, Edzná, Cobá, Lamanai, Komchen, Dzibilchaltun, and San Bartolo, among others.
The Preclassic in the central Mexican highlands is represented by such sites as Tlapacoya, Tlatilco, and Cuicuilco. These sites were eventually superseded by Teotihuacán, an important Classic era site which would eventually dominate economic and interaction spheres throughout Mesoamerica. The settlement of Teotihuacan is dated to later portion of the Late Preclassic, or roughly A.D. 50.
In the Valley of Oaxaca, San José Mogote represents one of the oldest permanent agricultural villages in the area, and one of the first to use pottery. During the Early and Middle Preclassic, the site developed some of the earliest examples of defensive palisades, ceremonial structures, the use of adobe, and hieroglyphic writing. Also importantly, the site was one of the first to demonstrate inherited status, signifying a radical shift in socio-cultural and political structure. San José Mogote would eventual be overtaken by Monte Albán, the subsequent capital of the Zapotec empire, during the Late Preclassic.
The Preclassic in western Mexico, in the states of Nayarit, Jalisco, Colima, and Michoacán also known as the Occidente, is poorly understood. This period is best represented by the thousands of figurines recovered by looters and ascribed to the "shaft tomb tradition".