The purpose of this study was to assess the impact of deliberate acts of kindness (DAKs) plus access to a stress management booklet (intervention), compared to the booklet alone (control) on the stress-related outcomes of resilience, social interaction anxiety, affect, and mood of undergraduate and graduate students. Participants’ study-related experiences were also explored, as were the types of DAKs. This repeated-measures, randomized controlled trial included 112 students (80 undergraduate and 32 graduate) with 56 in each condition. Four previously validated scales were implemented at baseline, immediate post-intervention, and 3-months post-intervention. A linear mixed effects model was utilized with group and time entered as fixed effects. Content analysis of open-ended question responses and DAKs logs was conducted. The KISS of Kindness II had a statistically significant interaction effect on the intervention group participants’ resilience (p = 0.0099), social anxiety (p = 0.0016), and negative affect (p = 0.0033), but had no significant impact on their positive affect or mood. Intervention participants described improvements in mental wellbeing. DAKs were plentiful (1,542 DAKs, 26 types), and show promise for university-based mental health interventions.