People with psychotic symptoms are reported to have a characteristic reasoning style in which they jump to conclusions. To date, little research has been conducted to investigate if this style changes over time and is associated with improvements or worsening of symptoms. This study considered these questions. Thirty-one service users were recruited from a first-episode service and completed measures of reasoning, psychotic, and non-psychotic symptomatology at two time points over 2 years. Over time, people with psychosis generally became less hasty in their decision-making. Those who became less hasty in their reasoning were less symptomatic. For those who remained very hasty in their reasoning, this was associated with a worsening specifically of the delusional beliefs. This work supports the notion that there is a critical time in the first few years of psychosis during which symptoms and reasoning can change. However, where reasoning style does not change, this may be associated with greater difficulties associated with delusional beliefs. © 2013 The British Psychological Society.