Parents worried about whether their teen’s moodiness is hormonal or something more serious can now get reliable information on depression off the smartphone in their purse or pocket.

mADAP, an app created by Johns Hopkins psychiatrists, is meant to provide dependable, handy information about teen depression to parents and teenagers. Roughly 2.8 million teens suffered at least one major depressive episode in 2014, according to the Substance Abuse and Mental Health Services Administration.

As part of the Adolescent Depression Awareness Program (ADAP), psychiatrist Karen Swartz visits schools to educate teens, parents and teachers about depression. She considers mADAP one more tool to reach families. “The next generation is probably more likely to sign up for and download an app than get a book from a library,” says Swartz.

Swartz and her colleagues began work on mADAP in 2011. Using free software, they built the prototype before securing $20,000 in department funding for an app developer to create, test and deploy a better version.

Users can click on the app’s stylized illustrations of teenagers to view Johns Hopkins psychiatrists explaining who’s at risk of becoming depressed and the difference between sadness and depression. They can also read about the symptoms, diagnosis and treatment of depression in adolescents.

“We wanted to strike a balance between something that would appeal to teenagers and something that would still take the topic seriously,” says psychiatrist Anne Ruble, who started the app project with psychiatry emergency service director Vinay Parekh.

mADAP includes information on what to do if you’re a teen feeling depressed—short answer: tell an adult, talk to your doctor—and links to resources, like a treatment locator. Launched last October, the free app is available for iOS devices and in a beta version for Galaxy S5 and S6 phones.