Lana Weinberger is the enemy of Mia Thermopolis in the earlier books, but eventually becomes one of her best friends towards the end of the series.
She is said to be "very beautiful" and is also the "party girl". She has long, stick-straight blond hair and Baby blue eyes. She is very popular, a cheerleader and is in Mia's grade at Albert Einstein High School. Lana is very spoiled by her dad, whilst Mia rarely sees her dad. Lana is actually very intelligent, but pretends not to be.
After Mia and Lilly become estranged, Lana makes a confession to Mia: she's jealous of her. So they agree on a truce, becoming best friends. Throughout the ninth and tenth book, Lana supports Mia, encouraging her to face Michael.
Lana dated Josh Richter until she found him and his friends hawking loogies off the Empire State Building on the night of the prom in Prom Princess, the fifth book in the series. One of Mia's friends, Tina Hakim-Baba, later told her that Lana began crying and then told Josh that what he did was how she was going to be forced to remember him when he left for college the following year.
Meg Cabot herself said that the fight between Mia and Lana is "a fight to the death because they have very different views of life".