The Fall Armyworm (Spodoptera frugiperda), also known as FAW, is a major food crop pest that was first detected in 2016 in Central and Western Africa, subsequently spreading rapidly throughout sub-Saharan Africa. ACDI/VOCA, an organization that implements food security projects in developing countries, responded through targeted, systemic interventions in agricultural focused projects located in Ghana (ADVANCE II), and Tanzania (NAFAKA II). Both projects launched localized scouting systems to monitor pest spread; developed strategic media campaigns and leveraged private-sector agribusiness providers and extension specialists to raise awareness of FAW; and spearheaded capacity building activities around management practices. Furthermore, Ghana staff facilitated field trials in 2017 and 2018 that examined the efficacy of various pesticides’ in reducing maize (Zea mays) ear damage. The Ghana project also created a call center for FAW sightings. NAFAKA II enhanced producer connectivity to input service providers and gave small grants to spray service providers and village based agricultural advisors to address FAW emergence. In 2018, seventy-seven and ninety percent of Ghana and Tanzania project participants, respectively, utilized the promoted FAW management practices and services. A comprehensive study composed of a randomized, statistically representative survey of engaged actors, key-informant interviews and stakeholder focus groups revealed the effectiveness of these interventions in managing the onset of a foreign pest such as FAW, including gaps and lessons learned.