We analysed how syntactic flexibility influences sentence production in two different languages-English and Russian. In Experiment 1, speakers were instructed to produce as many structurally different descriptions of transitive-event pictures as possible. Consistent with the syntactically more flexible Russian grammar, Russian participants produced more descriptions and used a greater variety of structures than their English counterparts. In Experiment 2, a different sample of participants provided single-sentence descriptions of the same picture materials while their eye movements were recorded. In this task, English and Russian participants almost exclusively produced canonical subject-verb-object active-voice structures. However, Russian participants took longer to plan their sentences, as reflected in longer sentence onset latencies and eye-voice spans for the sentence-initial subject noun. This cross-linguistic difference in processing load diminished toward the end of the sentence. Stepwise generalized linear model analyses showed that the greater sentence-initial processing load registered in Experiment 2 corresponded to the greater amount of syntactic competition from available alternatives (Experiment 1), suggesting that syntactic flexibility is costly regardless of the language in use.