<p>Fixed-lean schedule thinning involves programming the terminal reinforcement schedule from the onset of schedule thinning rather than gradually reducing the delay to reinforcement over time in a dense-to-lean approach. This study extended Sumter et al.&#xa0;(<CitationRef CitationID="CR32">2020)</CitationRef>&#xa0;and investigated the effect of continuous access to attention (an arbitrary stimulus; not functionally related to challenging behavior) during fixed-lean schedule thinning for individuals who engaged in challenging behavior maintained by tangible reinforcement or a combination of tangible reinforcement and escape. In some sessions, participants received continuous access to attention during reinforcement schedule thinning, and in others they waited without attention. Results demonstrated a similar reduction in challenging behavior across both conditions. However, two participants, along with the third participant’s caregiver, preferred the condition that included attention. This study expands upon existing research by examining the application of arbitrary stimuli within fixed-lean schedule thinning, suggesting that continuous access to attention may enhance treatment acceptability without disruptions to treatment efficacy.</p><p> • Fixed-lean schedule thinning programs the terminal reinforcement schedule from the start and may be more efficient than other schedule thinning approaches.</p><p> • Researchers have explored alternatives to traditional extinction during reinforcement schedule thinning, such as the addition of an arbitrary stimulus.</p><p> • Access to an arbitrary stimulus can help sustain low levels of challenging behavior during reinforcement schedule thinning.</p><p> • Access to an arbitrary stimulus may be preferred over no access.</p>