Using transfer methodology, several possible factors that could have affected the expression of serial position learning were examined with runway-trained rats. A 3-trial series (SNP) --for which S and P refer to series trials when sucrose (S) and plain (P) Noyes pellets were used as a reward, and N refers to a trial without reward -- was the basis for training in the first 2 and final experiments. Transfer tests in Experiment 1 altered reward memories, the time between trials in the series, or both. Tests in Experiment 2 altered the number of trials in the series while maintaining essential memory relationships. Experiment 3 involved a 4-trial series (PSNP or SPNS) and transfer tests with changed memory (NNNN). In Experiment 4, training on an RNR series, where R could be either S or P in either large or small magnitudes, was followed by a transfer test to NNN and a final test in which the rats were prevented from running on the 1st or 2nd series trial. The findings support a view that position and memory learning are compatible sources of serial effects, and they suggest temporal and response cues may not be crucial in position effects.