An experiment was conducted on the determination of effective spatial arrangement for intercropping of maize and potato using competition indices at South Wollo, Ethiopia for two consecutive years, 2010-2011. The objective of the study was to determine effective spatial arrangement for intercropping of maize and potato. The treatments were 1 maize:1 potato, 2 maize:2 potato, 1 maize:2 potato (a), 2 maize:1 potato (a), 1 maize:2 potato (b) and 2 maize:1 potato (b). Sole maize and sole potato was used for comparison. JMP 5 (SAS) software’s were used to compute the analysis of variance. The combined yield advantages in terms of total land equivalent ratio (LER) and Income equivalent ratio (IER) indices were greatest in the cases of 1 maize:1 potato followed by 1 maize:2 potato (b) intercropping arrangement. Area time equivalent ratio (ATER) values showed an advantage of 75.0% only in 1 maize:1 potato. Effective Monetary advantage (EMAI) index was highest in 1 maize:2 potato (b)followed by 1 maize: 1 potato intercropping arraignments.