Encoding variability refers to the situation in which repeated items are processed in different ways on each presentation. Superior memory performance resulting from encoding variability is sometimes argued to underlie important phenomena in human memory such as the spacing effect. However, the memory benefits of encoding variability are often elusive. Here we investigated encoding variability in ten experiments in which participants studied words with the same or different orienting tasks across repetitions. We have found the benefits of variable encoding to depend on the number of learning cycles and the retrieval demands at test. These results are interpreted in light of a distinction between different components of memory representations established at study, suggesting that encoding variability promoted via different orienting tasks--as implemented in the present study--fosters more elaborate encoding of semantic features. This augmented semantic component benefits memory performance only when a memory test is used that taps predominantly semantic features of memory representations, minimizing the role of contextual and relational factors.