Students are expected to recognize the vocabulary items appearing in a text in order for reading to be meaningful. The evaluation of word recognition is commonly considered in educational applications in order for reading to be meaningful for students and to identify and correct mistakes. This study aims to exhibit the effectiveness of the inventory whose stages of preparation and implementation were process-based and which was developed for word recognition on determining the first graders' word recognition levels. For this purpose, the Type 1 development research type of design and development research model was used to develop an instrument for students' word recognition levels and thus to demonstrate its applicability. The study group was composed of 85 first graders who had been chosen in convenience sampling method. Student Information Form, Word Recognition Inventory-1 (WRI-1) and Word Recognition Inventory-2 (WRI-2) were used as the tools of data collection. Variance analysis (ANOVA) and independent groups t-test were used in comparing the students for WRI-1 inventory which met the conditions for normal distribution whereas Kruskal Wallis and Mann Whitney U-test were used in comparing the students for WRI-2 inventory which did not meet the conditions for normal distribution. Consequently, it was found that the inventories, whose stages of preparation and implementation were process-based and which were developed to determine students' word recognition levels, were effective in determining the primary school first graders' word recognition levels.