Based on the existing literature, relevant determinants of availability for on-premises locations, off-premises locations, and the Internet were qualitatively explored and categorized by "experts" consisting of underage alcohol purchasers. In total, 14 focus group discussions were conducted with 94 Dutch adolescents. For on-premises locations, the high prices were perceived as the biggest disadvantage, and the ease to circumvent legal age limits as the biggest advantage. For off-premises locations, the cheap pricing was perceived as the most positive aspect, and the legal age limit as the biggest disadvantage. For online purchases, the waiting time was perceived as the most negative aspect, and the proximity of online stores as the biggest advantage.