This is an in-depth study of word knowledge where the researcher attempts to investigate the need to systematically teach vocabulary in the language classroom. It is motivated by findings within second language (L2) vocabulary testing research that state that the current communicative language learning environment is insufficient for L2 learners to acquire adequate vocabulary knowledge and L2 learners need help with vocabulary learning (Laufer, 2005). This semester-long study explores the need to provide explicit vocabulary instruction from within a meaningful environment. It also investigates the relevance of focus on forms and focus on form practices in helping second language (L2) learners increase the size and depth of word knowledge. The study involved 129 undergraduates from a writing program, and used a pretest and posttest design to measure gains in L2 learners vocabulary knowledge. .The results indicate that the vocabulary gains for both implicit (control) and explicit (treatment) instructional context were not very different though the subjects in the implicit instructional group learned slightly more words compared to the explicit instructional group. However, this has more to do with individual instructor effectiveness and learner proficiency. In terms of word use, L2 learners subjected to explicit focus on forms and focus on form tasks increased their word use while the first language (L1) learners and L2 learners from the control groups did not increase their academic words. Therefore, it is possible to suggest that L2 learners can be taught to increase the depth of their vocabulary knowledge through explicit instructional practices. In terms of L1 and L2 learners, the initial findings revealed that the L2 learners did not benefit from explicit instruction. However, additional analysis revealed that subjects with sufficient vocabulary knowledge at the 2000 word level can increase their word size much more rapidly than the proficient L2 learners in the control group. An additional test on L1 and L2 learners' word collocation skills indicated that while explicit instruction did not help increase L2 learners vocabulary size, it was able to help L2 learners increase their word collocation skills and also make word associations that are closer to L1 learners' associations.