This study examines the effects of age, cognitive resources, and task familiarity on planning performance. Fifty-two young and 52 old adults completed one of two errand-planning tasks. The tasks were matched for structure, difficulty, and format, but differed in content, such that one planning task required planning a real-world shopping tour whereas the other involved planning an unfamiliar space tour. In addition, the participants' memory capacity, speed of processing, inhibition, and memory for relevant versus irrelevant task features were assessed. Results revealed no age differences for the real-world planning material. In contrast, old adults performed worse than young adults in the artificial planning task. Data are discussed in the context of old adults possibly being able to compensate for cognitive deficits in speed and inhibition by selectively allocating resources to relevant task elements, but only if they perform a planning task containing elements that approximate their real-world experience with errand-planning problems.