This empirical study was undertaken to test the Involvement Load Hypothesis (Laufer and Hulstijn, 2001) by examining the impact of three tasks on vocabulary acquisition. It was designed to test and develop the involvement load hypothesis by examining the impact of different reading tasks on the L2 vocabulary acquisition. The results show that reading tasks could facilitate L2 vocabulary acquisition. The hypothesis is basically supported, but it is expected that it will be further improved and needs some modifications. Furthermore, the results also indicate that using new words in contextualized communication is an efficient means to extend and consolidate learners' vocabulary acquisition.