"Brothers and Sisters" was immediately successful. The record went gold in retail sales within 48 hours after shipping began. Capricorn estimated that these early sales were due to hardcore fans of the group. The album sold 760,000 copies in its first three weeks, making it one of the fastest-starting albums in Warner/Elektra/Atlantic Records' history. Billboard called it the "success story of the summer," noting that there was no "sustained merchandising promotion effort needed" on the LP. Record stores credited the album with bringing business back to their stores in a lagging season. "Brothers and Sisters" was the band's best-performing album on the charts: it logged five weeks as the number one album in the country on the "Billboard" Top LP's & Tape chart.