Much previous research has conceptualized pauses during writing as indicators of the engagement of higher-level cognitive processes. In the present study 101 university students composed narrative or argumentative essays, while their key logging was recorded. We investigated the relation between pauses within three time intervals (300–999, 1000–1999, and >2000 ms), at different text boundaries (i.e., between words, sentences, and paragraphs), genre (i.e., narrative vs. argumentative), and transcription fluency (i.e., typing speed). Moreover, we investigated the relation between pauses and various lexical characteristics of essays (e.g., word frequency, sentence length) controlling for transcription fluency and genre. In addition to replicating a number of previously reported pause effects in composition, we also show that pauses are related to various aspects of writing, regardless of transcription fluency and genre. Critically our results show that the majority of pause effects in written composition are modulated by pause location. For example, increased pause rates at word boundaries predicted word frequency, while pause rates at sentence boundaries predicted sentence length, suggesting different levels of processing at these text boundaries. Lastly, we report some inconsistencies when using various definitions of pauses. We discuss potential mechanisms underlying effects of pauses at different text boundaries on writing.