We conducted a meta-analysis to analyze the effects of randomized controlled positive psychological interventions on subjective and psychological well-being. Our aim was to extend previous research by following a more comprehensive approach in the selection of studies, by including new moderators, by focusing on adult nonclinical populations and increases in well-being, and by comparing the effects of interventions targeting subjective and psychological well-being (i.e., hedonism or eudemonia) or a combination of the two. In contrast to previous analyses, we compared effects on different outcomes and contrasted effects of technology-assisted interventions with traditional ones. We included 68 randomized controlled studies of nonclinical populations with a total of 16,085 participants. The results showed that positive psychological interventions do increase well-being. The overall effect size (Cohen's d) was 0.23, but it was 0.08 for psychological well-being, 0.22 for subjective well-being, and 0.43 when the studies targeted both types of well-being. Longer interventions showed stronger immediate effects than shorter ones, and interventions based on traditional methods were more effective than those that used technology-assisted methods. With respect to short-term outcomes, there was a negative relation to age, but when long-term effects were considered, the relation to age was positive. Overall, we also found evidence of long-term effects of the interventions.