The origin and reactions of dislocations in silicon web‐dendrite crystals are discussed. In particular, x‐ray topographs are compared with etching results. Dislocations having [21¯1¯] axes or ⟨110⟩ type axes have been characterized. In the former case, normal edge and 20° dislocations are seen; however, an apparently new dislocation with a [21¯1¯] axis and [101] type or [110] type of Burgers vector has also been observed. Dislocations having a [11¯0] axis and [110] Burgers vector have been identified and associated with the Cottrell‐Lomer reaction. The presence of multiple twin planes parallel to the growth direction of the web, accompanied by regions of very high dislocation density near the dendrites, increases the probability of certain dislocation reactions.