Bad Girl Good Girl

The song served as the group's debut single in June 2010.

An instant commercial success in South Korea,[1][2] "Bad Girl Good Girl" topped the Gaon Digital Chart and became the best-performing single of 2010.

On June 30, 2010, the music video for the song was released online.

The music video features the girls in a school, dancing in sync.

Miss A became number one again on KBS Music Bank the following day on July 23 and on SBS Inkigayo on August 1.