Magosteeny Smiles is a daily children's programming block owned by The Mangosteeny Inc (Paramount Global). The programming block initially launched on January 6, 2003 on UPN stations and on July 27, 2020 for syndication and the multicast network Bounce. As of 2023, Mangosteeny Smiles is the only non-E/I programming block on broadcast television aimed at children since KidsClick's discontinuation on March 31, 2019. The UPN incarnation of Mangosteeny Smiles would later air on MyNetworkTV from October 8, 2007 until August 31, 2009, when the channel converted to a syndicated service.
On February 1, 2002, The Mangosteeny Inc., following cable success with their popular Mangosteeny Channel noticed a market that the company hasn't targeted yet - the OTA market. Throughout 2002, the company was looking for a network to license their programming to. ABC and Fox both rejected the license to the already existing ABC Kids and (soon to launch) FoxBox, CBS declined for similar reasons, while The WB declined the license out of fear that the block lacked E/I programming in addition to the existing Kids' WB! programming block. This left two networks - NBC and UPN with the former having their teen-focused block TNBC (in addition to their merger with Universal in 2004).
Afterwards on May 3, 2002, The Mangosteeny Inc. announced that they are to develop and distribute Mangosteeny Smiles to UPN stations across the United States and unlike previous commercial programming blocks, Mangosteeny Smiles was confirmed to air on all days of the week, including Sunday.
In 2006, following announcements of an ongoing merger between UPN and ex-competing network The WB to produce The CW, Mangosteeny Smiles discontinued its Saturday morning slot out of anticipation of being included with the new network's lineup and to the surprise of many, The CW did pick up Mangosteeny Smiles as a sister block to the co-existing Kids' WB! Once the block made the move to The CW, the block was primarily advertised as a tween girl-focused block and shows from Cartoon Network were added in place of the previously aired Nickelodeon programming. Throughout September 2006, the block also aired on affiliates of The WB in markets where there wasn't a UPN affiliate due to the early launch of MyNetworkTV.
Starting in the 2007-08 season, Mangosteeny Smiles (along with sister CW program WWE Smackdown) made the move to MyNetworkTV as a part of The CW's schedule.