When Weezer released their second album, “Pinkerton,” in 1996, it was voted the second worst album of the year by the readers of Rolling Stone. This is strange considering that “Pinkerton” is now regarded as one of the best albums of the 90s and worshipped by many of the fans who detested it so much after a first listen. People don’t like it when their favorite bands develop and move in different directions, particularly when they evolve from classic pop songs to deeper and more troubling terrain. It takes time to appreciate why a band would want to do something different and surprise those that fell in love with them in the first place.

Los Campesinos! have taken on this challenge, trying to develop their original sound without losing their core fan base. Their new LP, “We Are Beautiful, We Are Doomed,” comes just six months after their debut album, “Hold on Now, Youngster...,” and the difference between the two albums is shocking. Whereas the debut was sunny, straight-forward, and buckets of fun, the follow-up is difficult to love and at times genuinely disturbing. There are still moments of indie pop bliss to be found, but there is an awful lot more to this album than that. It may well alienate some people, but “We Are Beautiful” is a stunning step forward for the band.

First track “Ways to Make It Through the Wall” bursts out as the most heavy-rocking song the band has yet put to record. It is a stunning opener, full of spiteful lyrics, distorted guitars, and a massive chorus. The lyrics (“We learn over time that tolerance is more appealing / In theory than in practice”) hint at growing up, if not necessarily the maturity that should come with it.

Later tracks show even greater development. “You’ll Need Those Fingers for Crossing,” possibly the tightest and most affecting song the band has yet composed, is about bulimia. When Gareth Campesinos! sings “I can taste the blood on your lips and on your tongue / I can see your teeth turn pink / Your gums fade to white,” it is hard to believe that this band was originally labelled as twee. Likewise, “Miserabilia” is a harrowing tale of failed love affairs and more eating disorders (“I’ve spent too much time on my knees next to urinals in garish Mexican restaurants.”)

On the debut, the vocals were shared fairly evenly between Gareth and Aleksandra Campesinos!, but here it is very clear who the true voice of this band belongs to. Most songs consist of long monologues by Gareth Campesinos!, held together by sing-along choruses. Although the interplay between two radically different voices was one of the highlights of their debut, the emergence of Gareth as a true frontman bodes very well for Los Campesinos!’s future, giving them a true personality and center for their songs.

Just as exciting are the musical advances on “We Are Beautiful.” In just six months the band has moved well beyond its previously simplistic songwriting by incorporating new influences and song structures. Closer “All Your Kayfabe Friends” and the title track both twist in myriad directions, always threatening to dissolve into chaos while just clinging to some semblance of structure. The influence of Pavement on the band is clearer than ever on the beautiful lo-fi ballad “Heart Swells/Pacific Daylight Time.” (It even has two parts!) Some of the experiments toward the end of the album fall a bit flat, giving the impression that Los Campesinos! are trying a little too hard to push boundaries without any real concept of where that will take them. But on the best tracks, the group has never sounded better.

The preoccupations of “We Are Beautiful”—eating disorders, vomiting, and self-loathing—certainly make one wonder what the band has been through since the release of their debut. Listening to this album can be an overwhelming experience, particularly when compared with the glorious escapism offered by “Hold On Now, Youngster.” However, that in just six months Los Campesinos! have managed to move on completely from their twee background, refine their song writing, and discover a charismatic front man is hugely impressive. Here’s hoping they don’t lose faith and start making albums as lightweight as “The Green Album.”

—Reviewer Chris R. Kingston can be reached at kingston@fas.harvard.edu.