Meaningful collective engagement to create equitable futures requires fundamentally different mindsets and practices than designers were typically trained for. This poster presents a horizontal design methodology developed through twenty years of fieldwork with Indigenous cooperatives, community leaders, and students in México and Florida, demonstrating the profound shifts required to move from designing for to designing with people in context. The horizontal framework draws from Indigenous research methodologies (Smith, 2021; Wilson, 2008; Chilisa, 2012), decolonial theory (Mignolo, 2011), and Latin American scholarship on horizontalidad (Corona Berkin & Kaltmeier, 2012). Central to this approach is recognizing that marginalized communities possess knowledges, strengths, and capabilities that dominant design paradigms systematically overlook. Rather than parachuting into contexts with predetermined solutions, horizontal design requires long-term commitments, reciprocity, and the humility to learn from those we work with as epistemological equals.