The main exposition of "PCT" is Alinei's Origini delle Lingue d’Europa, published in two volumes in 1996 and 2000.
The PCT posits that the advent of Indo-European languages should be linked to the arrival of Homo sapiens in Europe and Asia from Africa in the Upper Paleolithic. Empolying "lexical periodization", Alinei arrives at a timeline deeper than even that of Colin Renfrew's Anatolian hypothesis.
The continuity theory draws on a Continuity Model (CM), positing the presence of IE and non-IE peoples and languages in Europe from Paleolithic times and allowing for minor invasions and infiltrations of local scope, mainly during the last three millennia.
Arguing that continuity is "the archeologist's easiest pursuit," Alinei deems this "the easiest working hypothesis," putting the burden of proof on competing hypotheses as long as none provide irrefutable counter-evidence. Alinei also claims linguistic coherence, rigor and productivity in the pursuit of this approach.
The Paleolithic Continuity hypothesis reverses the Kurgan hypothesis and largely identifies the Indo-Europeans with Gimbutas' "Old Europe",. PCT reassigns the Kurgan culture (traditionally considered early Indo-European) to a people of predominantly mixed Uralic and Turkic stock. This hypothesis is supported by the tentative linguistic identification of Etruscans as a Uralic, proto-Hungarian people that had already undergone strong proto-Turkish influence in the third millennium BC, when Pontic invasions would have brought this people to the Carpathian Basin. A subsequent migration of Urnfield culture signature around 1250 BC caused this ethnic group to expand south in a general movement of people, attested by the upheaval of the Sea Peoples and the overthrow of an earlier Italic substrate at the onset of the "Etruscan" Villanovan culture.
A certain pan-European development is supported by archeological evidence, featuring a process of regional depopulation followed by repopulation in a "sparse wave" scenario. Hunter-gatherers may have migrated rapidly out of a refugial area to account for a disproportionate contribution to the genetic and linguistic legacy of the region. Most likely, this would have happened at the end of the coldest part of the Younger Dryas (around 10,800-9,400 cal. BC) or later, following the cold event at 6,200 cal BC.
PCT draws radically different conclusions about the rate of linguistic change from those of the "traditional" theories of Gimbutas and even Colin Renfrew, that instead compress all language evolution within the lapse of time starting with the theorized Neolithic or Chalcolithic expansions from the respective homelands. Moreover, a linear projection of the rapid rate of linguistic change observed in this lapse of time back into the Palaeolithic would yield completely different results.
The search for archaeological evidence beyond what can be motivated from historical linguistics has been criticized by linguist Kortlandt, considering the probability of irretrievable loss of many linguistic groups somewhere between the archeological horizon and the attestation of a language. Also, Kortlandt addressed a general tendency to date proto-languages farther back in time than is warranted by the linguistic evidence since, like with Romance languages, the linguistic impact of contact during the first expansions has proven to be decisive to the formative period. Against the ancient continuity of the Celtic language in Ireland he refers to the radical changes which embody the formation of Irish in the first half of the first millennium AD that are probably due to imperfect learning by speakers of an unknown substrate language which was lost forever. Kortlandt relates the earliest dialectal divergences within Slavic to the period of historically attested expansions, about the fourth century AD. Though reasonable to assume that many dialects arose and disappeared at earlier stages, the term “Slavic” would be inappropriate before the expansions of the first millennium AD. Accordingly, any proposal which goes back too much in time, say beyond the fifth millennium, would rather have to start from the possible affinities of Indo-European with other language families.
Linguist Peter Schrijver speculates on the reminiscent lexical and typological features of some northwestern European regions and assumes the preexistence of pre-Indo-European languages up to 9000 year ago, linked to the archeological Linear Pottery culture and to a family of languages featuring complex verbs, of which the Northwest Caucasian languages might have been the sole survivors: those influences would have been especially strong on Celtic languages originating north of the Alps and on the region including Belgium and the Rhineland, thus yielding some kind of other linguistic continuity rather that language continuity. This notion that Balkan farmers introduced a short lived non-Indo-European language into Europe is shared by Alinei, though so far the PCT does not accept the slight evidence this Balkan languages spread so far to the north.
In the field of cognitive linguistics Alinei draws on a synthesis of linguistic studies and on Noam Chomsky's consequences of innate grammaticality. The theory was derived as a development of the Uralic Continuity Theory.
In introduction to PCT Mario Alinei wrote
This, then, is a brief sketch of Alinei’s theory, which is both simpler than its rivals and more powerful in terms of the insights it provides into language in the Meso- and Palaeolithic. While his book contains some flaws I believe that it deserves to be regarded as one of the seminal texts on linguistic archaeology, although given its lamentable lack of citation in English-language circles, it appears that recognition will have to wait until a translation of the original Italian appears..''
Morris' review was reprinted as the foreword to the 2000 edition of Alinei's book..
Alinei's theory was again critically reviewed by Adiego Lajara (2002):