Results of 120 research studies were combined by meta-analysis to determine effects on mathematics test performance of factors other than knowledge of content. Effect sizes for 18 variables were derived by the method invented by Glass and tested for consistency and significance with inferential statistics provided by Hedges and Olkin. Conditions that enhanced performance included testwiseness training, praise, word-problem pictures, and frequent testing. Conditions that depressed performance included the use of “none of these” as a multiple-choice option and the presence of extraneous information in word problems. Conditions to which performance seemed insensitive included external reward, reproof, and placement of the question in word problems.