Leaving her boys home to step out for a good cause, Kate Middleton attended the Action on Addiction Gala in London on Thursday (October 24).

Wearing an elegant dark Jenny Packham silk tulle gown, the Duchess of Cambridge looked gorgeous and not at all fatigued from having a newborn baby.

According to the organization, Action on Addiction provides abstinence-based 12-Step residential treatment and structured day treatment.

Speaking about her little Prince's christening the day before, Kate told Sky News, "He was such a good boy actually. We were very lucky, he's not always like that."