EFL learners in two countries participated in two parallel experiments testing whether retention of vocabulary acquired incidentally is contingent on amount of task-induced involvement. Short- and long-term retention of ten unfamiliar words was investigated in three learning tasks (reading comprehension, comprehension plus filling in target words, and composition-writing with target words) with varying “involvement loads”—various combinations of need, search, and evaluation. Time-on-task, regarded as inherent to a task, differed among all three tasks. As predicted, amount of retention was related to amount of task-induced involvement load: Retention was highest in the composition task, lower in reading plus fill-in, and lowest in the reading. These results are discussed in light of the construct of task-induced involvement.