This study examined how heritage language and cultural funds of knowledge of Spanish-dominant Latinx immigrant families served as powerful resources for their concientización--critical awareness of important problems and social conditions--and bridged their cultural worlds of home, community, and school policy. The study drew on three complementary theories: Cultural Historical Activity Theory or Funds of Knowledge, Critical Pedagogy, and Bridging Multiple Worlds; all challenge common deficit models that these parents lack sufficient knowledge and concern for their children's formal education. Qualitative ethnographic study of Latinx immigrant parents in a parent engagement program revealed how dialogic interaction or plática, using colloquial funds of knowledge through dichos (words with extended metaphorical cultural significance) and refranes (proverbs conveying cultural wisdom about how to live and act), and cultural brokering from parent-coordinators helped parents author persuasive petition letters to school officials. The discussion addresses implications for research and practice supporting meaningful parent engagement.