About 27% of teenagers have some type of mental health disorder such as anxiety, depression and substance abuse. Depression is a serious disorder, most common in teenagers and often goes unnoticed. However, they can be detected early by teachers and we have effective treatments. Studies in European countries estimated the prevalence of adolescent depression around 12.55%, being more frequent in women. The prevalence increases with age and there are population studies that suggest that the high prevalence of depression is common in adolescents. One of the most important and most frequently associated with depression is suicide, becoming a serious health problem and constitute the third leading cause of death among adolescents between 15 and 24.

To estimate the prevalence of depression in adolescents in Spain. Rate sociodemographic variables associated.

Study desing: Observational, descriptive.

Study scope: Primary Care Health.

Subject of the study: Spanish students of 14 to 18 years old.

Variables to measure: Depression: Beck's depression index. Sociodemographics: Age, sex, course, repeater, number of siblings, smoker, drinker, toxic consumer, marital status of parents.

Sample size: It is calculated by accepting a signification level of 95%. A sample size of 2347 patients is estimated, including losses.

We will do an univariate analysis of qualitative variables by frequency and quantity by the mean, median and standard deviation. We will do a bivariate analysis using chi-square for qualitative variables and t test and ANOVA for qualitative as quantitative. Logistic regression will assess the factors that are associated with depression.