The Underworld star was a keen writer as a teenager, even winning two national competitions, and she wrote down her innermost thoughts in diaries as a young adult.
But she gave up her hobby after daughter Lily, now 13, took up reading for fear of embarrassing herself.
Beckinsale tells Britain's Hello! magazine, "I used to keep a diary, but as soon as Lily learned to read I stopped writing in it. Because children will find everything. You know how it is when a friend gives you a lollipop shaped like something really embarrassing, just for a joke? And you hide it away in what you swear is a safe place, and then your child comes home and she's like a heat-seeking missile - she finds it straight away and shows it to you and says: 'Mummy, what's this?'
"And I just know that it would be exactly the same situation if I were to keep a diary, so better not to."