“Wasted youth and a fistful of ideals,” a 25-year-old Billie Joe Armstrong sneers on “The Grouch,” a searing deep cut from Green Day’s essential fifth studio album, 1997’s Nimrod. “I had a young and optimistic point of view.”

The blistering song, about shattered dreams and the resulting apathy, was a world-weary flash of empathy that, like much of Nimrod, surprised upon its release on Oct. 14, 1997. Green Day wasn’t known for their reflectiveness — to most, they were the snot-nosed brats with neon hair who took over the airwaves in the mid-’90s with singles about masturbating in houses with unlocked doors and having eyes that felt like they were gonna bleed.

Nimrod emerged from the uncertainty that followed Green Day’s commercial breakthrough. After becoming legends of the East Bay’s underground punk circuit, thanks to their raucous shows at Berkeley’s beloved Alternative Music Foundation — colloquially known as “Gilman” — the band went nine-times platinum with 1994’s Dookie and notched another smash with its follow-up, 1995’s Insomniac. The records earned them international fame, but alienated many early fans, who accused Green Day of selling out — even if the LPs channeled the same irreverent pop-punk on which they’d built their name.

Green Day didn’t answer by doubling down on their formula or getting political (yet). Instead, they released Nimrod, a genre-hopping, 18-song opus that remains the most underrated entry in their expansive catalog. Twenty years after its debut, and with a vinyl reissue out today, Nimrod deserves proper recognition as one of the band’s masterpieces.

Like the Clash did on London Calling, Green Day turned stylistic impurity into its own form of punk defiance on Nimrod. Unexpected sounds populate the record, from the serene, instrumental surf-rock of “Last Ride In” to the wheezing harmonicas of “Walking Alone.” The biggest surprise is “King for a Day,” a brassy ska rush that’s since evolved into the extended climax of Green Day’s live shows.

Nimrod also has flashes of edgy intensity absent from relatively sanitized radio hits like Dookie‘s “Basket Case” and “When I Come Around.” With breakneck tempos, hardcore nuggets “Platypus (I Hate You)” and “Take Back” careen across their brief runtimes on the verge of collapse, as Armstrong spews vitriol. The dark themes paralleled the frontman’s personal demons. “During Nimrod, my drinking took off,” he told Rolling Stone in 2013, citing the album’s pummeling lead single, “Hitchin’ a Ride,” as particularly autobiographical. “Cold turkey’s getting stale/ Tonight, I’m eating crow,” he sings, before reaching its chorus: “I’m off the wagon, and I’m hitchin’ a ride.”

But despite its eclecticism and troubled undercurrent, Nimrod‘s defining trait is Armstrong’s deep emotional intelligence. Though Armstrong married his wife, Adrienne, in 1994, and the couple had their first child the following year, the album’s lyrics aren’t schmaltzy. Instead, they’re multidimensional analyses of love, commitment, and the concerns that accompany settling down. “Worry Rock” and “Redundant” tackle the “sentimental argument[s]” and good-faith spats that characterize passionate relationships, while “All the Time” conveys domesticity’s tedium, as Armstrong wryly describes “having the time of my life, watching the clock tick.” Armstrong’s preternatural understanding of issues far beyond his years echoes the enduring ballads Paul McCartney wrote at the Beatles’ zenith — and Green Day’s clean, immediate instrumentals on cuts like “Scattered” and “Uptight” only bolster the likeness.

Young as he was during the Nimrod sessions, Armstrong was practically a card-carrying AARP member compared to when he wrote “Good Riddance (Time Of Your Life”): He penned the album’s most iconic tune in 1990 at the age of 18. After excluding the song from Dookie and Insomniac, Green Day slotted it penultimately on Nimrod, before the cynical, anthemic closer “Prosthetic Head.” The two-and-a-half minute tune feels sheepishly tucked away, an earnest phrase muttered under the assumption few are paying attention. But as listeners have discovered repeatedly for the last two decades, “Good Riddance” contains multitudes.

Driven by plucky acoustic guitar and tear-jerking strings, “Good Riddance” bears little resemblance to the power chords that’d long defined Green Day — and Armstrong’s lyrics and vocal performance are even more arresting. The frontman originally intended the tune as a melancholy, sarcastic kiss-off to a girlfriend who’d broken his heart, but its ambiguous verses allowed audiences to project their own interpretations onto it. The song has soundtracked countless graduation ceremonies, wedding receptions, and even the Seinfeld finale because of that understated universality. For some, the line “it’s something unpredictable, but in the end it’s right,” tempers sadness in the wake of great adversity; for others, it assuages the fear of the future that comes with finishing life’s best chapters.