Intercropping is considered as a promising system having multi-dimensional advantages such as improved yield on sustained basis, effective use of land and other resources and reduction in cost of production. The present study was carried out using pea and three non-legume winter vegetables, i.e. garlic, turnip and cauliflower, by planting as sole crops and in pea–garlic, pea–turnip and pea–cauliflower intercropping systems to determine the competition among these vegetables and economics of each intercropping system. The intercropping systems were assessed on the basis of existing competition and economic indices such as land equivalent ratio (LER), relative crowding coefficient (K), aggressivity (A), competitive ratio (CR), actual yield loss (AYL), intercropping advantage and monetary advantage index (MAI). Yields of individual vegetables were higher when grown as sole crops compared with their intercropping with pea. Harvest index for pea was higher when grown alone or intercropped with garlic and was significantly reduced when intercropped with turnip or cauliflower. Harvest indices for garlic, turnip and cauliflower were statistically similar when grown as sole crops or intercropped with pea. The partial LER, K, A and CR for pea were higher in pea–garlic intercropping. However, partial LER, K, A and CR for intercrop were significantly higher for cauliflower and turnip in pea–cauliflower and pea–turnip intercropping systems respectively. The product of relative K values was greater for pea–garlic intercropping system, indicating a definite yield advantage. A similar trend to LER was followed by AYL. These results indicate that pea was more competitive than garlic, and cauliflower and turnip were more competitive than pea for exploiting the available growth resources. The highest MAI value was recorded for pea–garlic intercropping, reflecting that this intercropping system was more advantageous compared with other intercropping systems, indicating definite yield and economic advantages. However, pea–cauliflower intercropping system resulted in higher net income and benefit cost ratio.