<p>Evidence points to a mental health crisis among young people. To address their unmet mental health needs, students have turned to social media and other online platforms to seek mental help and advocate for better mental health. According to resource theory, tangible (e.g., social media and other digital technologies) and intangible resources (e.g., mental health literacy, social media competence) may bolster young people’s engagement in mental health advocacy. Drawing from a sample of 157 Filipino senior high school students from a private university, this convergent mixed methods study aims to (1) describe online mental health advocacy engagement; and (2) examine resources related to their engagement. Quantitative (i.e., scales) and qualitative data (i.e., open-ended questions) were collected via an online survey. Findings suggest that latent engagement (i.e., mental health information consumption) is the more commonly practiced online mental health advocacy engagement, followed by follower and expressive engagement (i.e., sharing mental health-related posts). Another identified form of online advocacy engagement is the provision of mental help via online platforms. Moreover, two major resources for online advocacy engagement surfaced from the integrated findings: <i>digital affordances</i>, which include social media presence and other related digital tools, and the “<i>self</i>,” which encompasses the youth advocate’s mental health literacy, social media competence, assessment of health (mis)information, and well-being. Insights from this study can assist mental health advocacy groups in designing and implementing initiatives to increase the participation of youth advocates.</p>