Many field professionals and scholars have requested a brief measure of Y-AP.  Well, here it is. The measure is 11 items long and assesses two primary components of youth-adult partnership: youth voice in decision making (YVDM) and supportive adult relationships (SAR).  The measure was validated with a highly diverse sample of young people from the United States, Malaysia, and Portugal.  The final publication is available at link.springer.com or can be read here:  Y-AP validation paper – AJCP

The article is dense. However, check out Table 2 in the article and the items are clearly written for you to use in assessing your own programs (or print the Youth Adult Partnership Assessment Tool available here). The bibliography has citations for other measures of youth voice that might interest you.