This study uses ecological momentary assessment (EMA) with smartphone devices to examine community adolescents’ perceptions regarding both the intensity of and variability in their daily sadness/depression, anxiety, and somatic problems over the period of one week. Participants were 90 high-school students (Mage = 14.61, SD = 1.64; range 12–18). The sample was divided according to gender (61.1% girls), migratory status (68.5% Spanish nationals and 31.5% Latin American immigrants), and level of psychological symptoms (17% risk group). Sadness/depression, anxiety, and somatic problems were examined using a smartphone app, five times per day, semi-randomly, for seven days (35 possible moments). A high proportion of adolescents did not report feelings of sadness (80.0%) or worry (79.3%) or physical symptoms on a daily basis (84.9%). Girls and the risk group reported greater intensity levels for the three analyzed problems than did boys and the normal group, respectively (p < .001 in all cases). Migratory status was not associated with any significant differences in the analyzed problems over the one-week period (p > .05 in all cases). Day-to-day fluctuations in mood during the week were statistically significant but not meaningful (b = 0.0004, 95% CI [0.0001, 0.0008], p = .001).