Social net works' influ ence on migra tion has long been explored largely through the lenses of cumu la tive cau sa tion and social cap i tal the ory. This arti cle aims to reconceptualize ele ments of these the o ries for the case of rural-urban migra tion and test their util ity in explaining first-migra tion tim ing. We use a uniquely exten sive social net work sur vey linked to pro spec tively col lected migra tion data in rural Senegal. We decom pose migrant net works into return migrants, cur rent migrants, and non mi grant res i dents of the des ti na tion to cap ture het ero ge ne ity in migra tion-rel e vant social cap i tal. As expected, the num ber of non mi grant alters liv ing in the cap i tal, Dakar, has an outsized asso ci a tion with the migra tion haz ard, the num ber of cur rent migrants from the vil lage liv ing in Dakar has a smaller asso ci a tion, and the num ber of return migrants has lit tle asso ci a tion. Drawing on social cap i tal the ory, we test the influ ence of (1) sub jectively assessed tie strength between the ego and their net work alters and (2) struc tur ally weak ties mea sured through sec ond-order ("friend of a friend") con nec tions. Weak and strong sub jec tive ties to cur rent migrants and non mi grant Dakar res i dents are pos i tively asso ci ated with the first-migra tion haz ard. Structurally weak ties to cur rent migrants are too, but only for indi vid u als with no direct ties to cur rent migrants.