The present study used event-related potentials and dipole source modeling to investigate dimension specificity in attentional control. Subjects performed cued attention tasks in which the task-relevant information (a) was always the same, (b) varied between features within the same dimension, or (c) varied between features of two different dimensions. Thus, both demands on control processes involved in generating an attentional set and the dimension (color or location) of the task-relevant feature were varied. Attentional control was associated with a dorsal posterior positivity starting at 260 ms postcue, which was stronger over left posterior scalp regions from 580 ms onward, especially when color was task relevant. This positivity likely reflects generic processes involved in the generation of an attentional set that were followed in time by dimension-specific processes related to the persistence of the task-relevant information in working memory.