Linguistic analyses suggest that there are two types of intransitive verbs: unaccusatives, whose sole argument is a patient or theme (e.g., fall), and unergatives, whose sole argument is an agent (e.g., jump). 1 Past psycholinguistic experiments suggest that this distinction affects how sentences are processed: for example, it modulates both comprehension processes ( Bever and Sanz 1997 , Friedmann et al. 2008 ) and production processes ( Kegl 1995 , Kim 2006 , M. Lee and Thompson 2004 , J. Lee and Thompson 2011 , McAllister et al. 2009 ). Given this body of evidence, it is reasonable to assume, as we do here, that this distinction is directly relevant to psycholinguistic theorizing. However, especially in production, exactly how this distinction affects processing is unknown, beyond the suggestion that unaccusatives somehow involve more complex processing than unergatives (see J. Lee and Thompson 2011 ). Here we examine how real-time planning processes in production differ for unaccusatives and unergatives. We build on previous studies on lookahead effects in sentence planning that show that verbs are planned before a deep object is uttered but not before a deep subject is uttered ( Momma, Slevc, and Phillips 2015 , 2016 ). (We use terms like deep subject in a theory-neutral fashion, with no intended commitment to a specific syntactic encoding.) This line of research sheds light on the broader issue of how the theory of argument structure relates to sentence production. [ABSTRACT FROM AUTHOR]