An experiment was conducted at two locations and for two seasons in Ethiopia to quantify the relative effects of sowing date and method, fertilizer, and weed control on seed and oil yields and seed-yield components of Ethiopian mustard (Brassica carinata A. Braun.) and rape seed (B. napus L.). Use of N and P fertilizers, optimum sowing dates, and weed control invariably promoted seed and oil yields and number of pods per plant. The influence of sowing method was not consistent. There was a positive compensation of oil content by seed size. The indigenous species B. carinata, unlike the exotic B. napus, was found to be less fastidious in respect of the major culture practices.