"How Will I Know" is the third hit single from Whitney Houston's self-titled first album. The single was released in November 1985 and was written by George Merrill and Shannon Rubicam of Boy Meets Girl fame, who wrote it for Janet Jackson. The song is an electric dance tune about the singer wondering if a guy she likes feels the same way about her. Houston became a staple on MTV with the release of this hit single.

On the U.S. Billboard Hot 100 singles chart, "How Will I Know" reached the #1 spot on February 15, 1986, becoming Houston's second number-one single and third top five single from the same album. The single displaced "That's What Friends Are For" by Houston's cousin Dionne Warwick, thus becoming just the third time (and first time by female artists) in history for relatives to replace each other at number one on the Hot 100. It remained at number one for two weeks, and spent fifteen weeks in the top forty. It was ranked #6 on Billboard's top year end pop charts. The song performed extremely well on other Billboard charts as well, climbing to number one on the Adult Contemporary, Hot Black Singles, and Hot Dance Club Play charts, showing Houston's success was not limited to any single genre. Internationally, the single made Houston a noticeable star, reaching number five in the United Kingdom. The song may be heard in its original version, or in an extended percussion intro version (such as in the music video). Later copies of Houston's debut album contain the latter version.

The music video for "How Will I Know" was directed by Brian Grant and is set against a fantasy, vividly colored background, with dancers in black outfits and wearing French-style makeup. The video is recognized for the animated paint dripping down the screen. In the video, when Houston sings "I'm asking you 'cause you know about these things", there's a brief screencap of singer, close family friend, and godmother Aretha Franklin. Notable, too, is that the melody of "How Will I Know" closely samples the chorus melody of Aretha's earlier 1985 hit, "Who's Zoomin' Who", which was a relatively popular hit and also produced by Narada Michael Walden, hence her paying homage to her as well.