On June 15, 2000, a few months after Viacom completed its $37 billion merger with CBS Corporation, CBS reached an agreement with new corporate sister Nickelodeon to air programming from its Nick Jr. television block beginning that September. On September 16, 2000, the new four-hour block, Nick Jr. on CBS, premiered, replacing CBS Kidshow, which produced by Canada-based animation studioNelvana. The block ended its run the week prior on September 9. For the first two years of the Viacom agreement, the block exclusively aired preschool-oriented programming from Nick Jr., including interstitials from the Nickelodeon block's animated mascot, Face. On September 15, 2001, the block was reduced by one hour, reducing its length to three hours and removing Maggie and the Ferocious Beast and Maisy to make room for The Saturday Early Show. One week later, the block had a rebrand, adding shows like Oswald and Bob the Builder. On September 14, 2002, the block was rebranded from Nick Jr. on CBS to simply Nick on CBS; at that time, its programming content expanded to animated Nickelodeon series aimed at children between the ages of 2 to 12, in addition to two Nick Jr. series. As with the predecessor Think CBS Kids and CBS Kidshow blocks, all of the programs within the block complied with educational programming requirements defined by the Children's Television Act, although the educational content in some of the programs was tenuous in nature. It was partly for this reason why some of Nickelodeon's most popular programs were mainly not included as part of the CBS block, especially during the more open-formatted Nick on CBS era. However, occasional airings of SpongeBob SquarePants as well as The Fairly OddParents, Doug, Rocko's Modern Life, CatDog, , and Rocket Power appeared during special holiday events on the block. Rugrats also aired briefly in 2003, when it was added as a short-lived regular series within the block. Sometime in early 2004, the block had a relaunch, making additions like live-action shows, such as The Brothers García. The older-skewing Nickelodeon series were removed from the block and the revival of Nick Jr. on CBS was premiered on September 18, 2004 refocusing the block back exclusively toward preschool-oriented series; the block also began incorporating interstitial hosted segments featuring Piper O'Possum. On December 31, 2005, Viacom formally split under the shared control of National Amusements, with CBS and all related broadcasting, television production and distribution properties as well as some non-production entities becoming part of the standalone company CBS Corporation, while Nickelodeon and its parent subsidiary MTV Networks became part of a new company under the Viacom name. Less than a month later on January 19, 2006, CBS announced that it would enter into a three-year programming partnership with DIC Entertainment to produce a new children's program block for the three-hour Saturday morning timeslot featuring new and former series from its program library, to begin airing in Fall 2006. On September 9, 2006, Nick Jr. on CBS ended its run and was replaced with a new block the following weekend called KOL Secret Slumber Party. Following the announcement of the second merger between CBS Corporation and Viacom, former CBS Corporation CEO Joseph Ianniello was receptive to the possibility of the return of Nickelodeon children's programming to CBS. However, CBS is currently under contract with Litton Entertainment to carry the CBS Dream Team E/I programming block until the end of the 2022-23 television season, and any return of Nickelodeon programming would have to comply with the FCC's E/I requirements, including for advertising.
Programming
All of the programs aired within the block featured content compliant with educational programming requirements as mandated by the Federal Communications Commission via the Children's Television Act. Though the block was intended to air on Saturday mornings, some CBS affiliates deferred certain programs aired within the block to Sunday mornings, or Saturday afternoons due to breaking news or severe weather coverage, or regional or select national sports broadcasts scheduled in earlier Saturday timeslots as makegoods to comply with the E/I regulations. Some stations also tape delayed the entire block in order to accommodate local weekend morning newscasts, the Saturday edition of The Early Show or other programs of local interest.
