Six studies were performed investigating the relationship between digit span (DS) capacity and other memory and problem solving tasks: (1) Ss were administered a DS test, an aurally presented mental addition test, a similar multiplication task, and a written timed division test. DS correlated only with the second; (2) Ss were required to interchange mentally the letters in the corners of a square. This task did not correlate with DS; (3) free recall of series of 10 two-digit numbers did not correlate with DS; (4) Ss were presented multiple series of two-digit numbers, from five pairs up to 10 pairs. DS correlated highest using sets of six and seven number pairs; (5) the relationship between DS and memory for visual patterns was examined; with no correlation; (6) the relationship between DS and verbal memory was investigated using the immediate recall, recall after one presentation of a series, vocabulary, and DS. The first three tests correlated significantly with each other while DS did not correlate significantly with any of the three. It was concluded that a DS test measures a narrow ability which does not play a significant role in most other problem solving tasks. (Author/CJ)