Introduction: The spread of the COVID-19 Pandemic led the Italian government to impose restrictive measures. Schools were closed and the organization of Distance Learning (DL) made adolescents face the psychological impact of the pandemic and the loss of their social life. Objective: This research aimed to evaluate the psychological impact of the COVID-19 Pandemic and DL on students, attending two high schools in the Lodi area (Lombardy, Italy). Method: A questionnaire, composed of PSYCHO-COVID 19 and EMOTION THERMOMETER applied to DL, was administered anonymously through the Google Drive School platform, from May 5th to June 5th 2020. Results: Analysis of the protocols revealed stress reactions in 35% of students (12% High, 7% Moderate, 16% Mild). Principal Components Analysis also revealed the presence of a “distress entity” characterized by anxiety, depressive and somatic symptoms (comparable to those of post-traumatic stress syndrome), with a greater impact on females. The analysis of data on DL showed that online teaching was experienced negatively, in an almost linear correlation, by those subjects who had expressed distress. Conclusions: The results suggest that the pandemic had a traumatic impact on adolescents, especially on girls; psychological distress negatively influenced individual experiences with DL. Appropriate psychotherapeutic interventions are needed to prevent the chronicization of stress reactions and to facilitate the adaptation of adolescents to possible rapid changes in educational management.