Grammaticality judgment tests (GJTs) have been used to elicit data reflecting second language (L2) speakers' knowledge of L2 grammar. However, the exact constructs measured by GJTs, whether primarily implicit or explicit knowledge, are disputed and have been argued to differ depending on test-related variables (i.e., time pressure and item grammaticality). Using eye-tracking, this study replicates the GJT results in R. Ellis (2005). Twenty native and 40 nonnative English speakers judged sentences with and without time pressure. Analyses revealed that time pressure suppressed regressions (right-to-left eye movements) in nonnative speakers only. Conversely, both groups regressed more on untimed, grammatical items. These findings suggest that timed and untimed GJTs measure different constructs, which could correspond to implicit and explicit knowledge, respectively. In particular, they point to a difference in the levels of automatic and controlled processing involved in responding to the timed and untimed tests. Furthermore, untimed grammatical items may induce GJT-specific task effects.