The objective of this project was to develop a multiple choice test of graphing skills appropriate for science students from grades seven through twelve. Skills associated with the construction and interpretation of line graphs were delineated, and nine objectives encompassing these skills were developed. Twenty-six items were then constructed to measure these objectives. To establish content validity, items and objectives were submitted to a panel of reviewers. The experts agreed over 94% of the time on assignment of items to objectives and 98% on the scoring of items. TOGS was first administered to 119 7th, 9th, and 11th graders. The reliability (KR-20) was 0.81. Poorly functioning items were rewritten based on the item difficulty and discrimination data. The revised version of the test was given to 377 7th through 12th grade students. Total scores ranged from 2 to 26 correct (X = 13.3, S.D. = 5.3). The reliability (KR-20) was 0.83 for all subjects and ranged from 0.71 for eighth graders to 0.88 for ninth graders. Point biserial correlations showed 24 of the 26 items above 0.30 with an average value of 0.43. It was concluded from this and other data that TOGS was a valid and reliable instrument for measuring graphing abilities.