The broadcast, mired in third place before her arrival, was seen by 10.1 million viewers on Wednesday. ABC's "World News" was second with 7.1 million, while NBC's "Nightly News" had 7 million, according to Nielsen Media Research.
While Couric's audience was down from the nearly 13.6 million who watched her debut Tuesday, the second win was an encouraging sign for the CBS Corp. Most of the networks say it will take weeks or months before a true picture of the new viewing habits emerge.
Couric's broadcast on Wednesday featured her interview with President Bush.