Marc Boegner’s mission efforts are not exhausted by his term (1948-1968) as president of the executive board of the Société des Missions évangéliques de Paris (SMEP), but it does cover a decisive period in the history of SMEP, which was facing the rise of ecclesiastical autonomy in nine mission fields in Africa, Madagascar, and the Pacific and experiencing demise as a society originating in the nineteen-century Réveil. Boegner’s missionary conscience was awakened at the turn of the twentieth century, under the influence of two uncles, the pastors Tommy Fallot and Alfred Boegner. The former, whom Boegner was to succeed in the parish of Aouste (Drôme) in 1904, was at the origins of his vocation as pastor and his discovery of the principles for the synodicalization of the missionary movement. The latter, who in 1911 appointed Boegner to be director of the SMEP seminary, shaped his spirituality. Boegner joined the executive board in 1919, and from that time until his appointment as vice-president in 1939, reflected on two topics of fundamental importance for his activity. The first was the structural connection between mission and the unity of the church, and second the problematic relation between mission and colonization. Among the events that tested his mission conscience, yet without weakening it, one must mention his journey to Madagascar following the Malagasy Uprising of March-April 1947. There he discovered that the Malagasies’ claims to independence ought to be granted, without confusing them with those at the basis of the churches’ claim to autonomy. This experience was to guide Boegner in later visits to other churches to which he, in the name of the SMEP, would grant autonomy.