This study investigated the effect of search and evaluation on vocabulary learning based on the involvement load hypothesis. Search and evaluation are cognitive components of task-induced involvement. This research examined how Korean university students at different English proficiency levels sought for and processed target words when engaging in productive word-focused tasks. Three types of tasks were used: gap-filling, gap-filling through word transformation, and writing original sentences. While these tasks have the same total involvement load, they differed in their specific levels of search and evaluation. To explore whether the differential distribution of search and evaluation could lead to varying search patterns and cognitive processing of target words, a think-aloud method, in-depth interviews, and observations were employed. All qualitative data were transcribed, analyzed, and coded using NVivo 14. Results indicated that the higher the index of search and evaluation, the more frequently searches and evaluations occurred. However, types of vocabulary knowledge searched in a dictionary, methods and purposes of using dictionaries, and the degree of cognitive involvement with target words varied according to proficiency level.