|This article's lead section may not adequately summarize key points of its contents. (January 2017)|
|Date of birth||5 May 1958|
|Place of birth||Ponte San Giovanni, Italy|
Cosmi was born in 1958 in Ponte San Giovanni, a Perugia frazione. His father, a cycling fan, called him Serse after Fausto Coppi's brother, a cyclist himself, who died following a fall during a sprint. He worked nine years as primary school teacher, and played amateur football during his freetime for local teams such as Deruta, Cannara, Spello and Pontevecchio, in the role of midfielder.
He started a coaching career in the late 1980s in Ellera, as under-18 youth team coach. His debut as first team coach came in 1990, when he was appointed to coach Pontevecchio, a small amateur team from his native town of Ponte San Giovanni. Cosmi brought it on from the Prima Categoria (fourth level of amateur leagues in Italy) to Serie D (the top one) in just five years. Successively, he joined Arezzo, which he led from Serie D to Serie C1 in five extremely positive years.
After being noted by Luciano Gaucci, in 2000 Cosmi was surprisingly appointed head coach of Perugia, in the Serie A. He guided the team for four consecutive years, winning a UEFA Intertoto Cup, showing valid coaching abilities and launching several players, including 2006 FIFA World Cup winner Marco Materazzi (who reached a career high of 12 goals in a single season under Cosmi's tenure), then-unknown Japanese Hidetoshi Nakata, Fabrizio Miccoli, Fabio Grosso and Fabio Liverani. Cosmi's period at Perugia would last four years, during which he led the fringe Umbrian club to victory in the 2003 UEFA Intertoto Cup.
Genoa and Udinese
At the end of the 2004–05 season, Cosmi managed to win the league and guide his team to Serie A, but he successively left because of discords with club chairman Enrico Preziosi, before the relegation of Genoa itself to Serie C1 because of match frauds.
After his short, but successful, experience with Genoa, Cosmi was signed as new coach of Udinese, in order to replace Luciano Spalletti, who gained the qualification to the preliminary rounds of Champions' League the previous season. But it was Cosmi who led the team on the European competition, defeating Sporting Clube de Portugal in a two-tier qualifying round.
However, after a disappointing series of results, including elimination in Champions League and results in Serie A much below the expected results, Cosmi was finally fired on 10 February 2006.
Brescia and Livorno
On 28 February 2007 he was appointed head coach of Serie B club Brescia. On his very first match after replacing Mario Somma, Cosmi led Brescia to an astonishing 3–1 result against Serie B leaders Juventus. He was fired on September 2008 due to poor result to make room for new boss Nedo Sonetti.
On 20 October 2009 Cosmi made a Serie A comeback as new head coach of bottom-placed relegation battlers Livorno. In his first game in charge, he guided Livorno to a surprising 1–0 away win against AS Roma, which was immediately followed by a second consecutive 1–0 win, against Atalanta, only three days later.
Despite fairly good results at the helm of Livorno, Cosmi resigned from his coaching post on 24 January 2010, in the wake of a 2–0 home loss to fourth-placed Napoli due to disagreements with club chairman Aldo Spinelli. Two days later, on 26 January, Cosmi and Spinelli met each other in attempt to clarify each other, also following the supporter fanbase's criticism of the way Spinelli handled the issue. Following the meeting, both parties agreed that the head coach's resignation offer would have been rejected and Cosmi would return at Livorno with immediate effect. This however lasted only a few more weeks, and Cosmi was dismissed later on April following a string of negative results that left Livorno down at the bottom of the table.
After more than a year without a job, Cosmi returned into management on 28 February 2011, taking over coaching duties at Palermo as a replacement for Delio Rossi, who was dismissed from the Sicilian club following a record 0–7 home defeat to Udinese. At Palermo, Cosmi reunited with former players Fabrizio Miccoli and Fabio Liverani, as well as ex-player and team staff member Giovanni Tedesco.
On 24 February 2014, Cosmi returned into management as new head coach of Serie B club Pescara, replacing Pasquale Marino but failing to turn the team fortunes and missing out qualification for the promotion playoffs. He left the club by the end of the season.
On 11 March 2015 he was named manager of Serie B side Trapani replacing long time manager Roberto Boscaglia. Cosmi led Trapani to the 2016 Serie B promotion playoffs, where they were defeated by Pescara in the final round. He was sacked by Trapani on November 28, 2016, after obtaining only 11 points from the first 16 rounds of the 2016-17 season and having his car set on fire by the club's supporters.
- As of 28 November 2016
|Arezzo||1 July 1995||30 June 2000||187||77||65||45||41.18||226||177||+49|
|Perugia||1 July 2000||30 June 2004||168||55||53||60||32.74||214||231||–17|
|Genoa||1 July 2004||30 June 2005||45||20||20||5||44.44||79||50||+29|
|Udinese||1 July 2005||10 February 2006||36||12||8||16||33.33||44||54||–10|
|Brescia||28 February 2007||25 September 2008||69||34||16||19||49.28||96||69||+27|
|Livorno||21 October 2009||24 January 2010||15||7||0||8||46.67||13||21||–8|
|Livorno||26 January 2010||5 April 2010||11||0||5||6||0||9||19||–10|
|Palermo||28 February 2011||3 April 2011||4||1||0||3||25||1||7||–6|
|Lecce||4 December 2011||27 June 2012||25||6||10||9||24||29||33||–4|
|Siena||27 June 2012||17 December 2012||19||6||5||8||31.58||22||26||–4|
|Pescara||24 February 2014||30 June 2014||16||4||4||6||25||16||20||–4|
|Trapani||11 March 2015||28 November 2016||78||30||26||22||38.46||101||95||+6|
- Perugia (2000–2004)
Cosmi is widely popular in Italy for his excitable behaviour during matches. He is also famous for always wearing a baseball cap (usually that of his team, but often with just his signature printed on it). Together with Carlo Mazzone, he is considered one of the most passionate coaches in Italian football, and also became subject of a satirical imitation from comedian Maurizio Crozza.
- (Italian) 
- (Italian) 
- (Italian) 
- Livorno Fans see Red – all the Time by Ian Hawkey, The National, February 5, 2010
- "Rottura con Spinelli Cosmi si dimette" (in Italian). La Repubblica. 24 January 2010. Retrieved 2010-01-24.
- "Respinte le dimissioni. Cosmi resta al Livorno" (in Italian). AS Livorno Calcio. 26 January 2010. Retrieved 2010-01-26.
- "Cambio alla guida tecnica: Ruotolo allenatore" (in Italian). AS Livorno Calcio. 5 April 2010. Retrieved 2010-04-06.
- "ROSSI SOLLEVATO DALL'INCARICO" (in Italian). US Città di Palermo. 28 January 2011. Retrieved 28 January 2011.
- "COSMI E' IL NUOVO ALLENATORE" (in Italian). US Città di Palermo. 28 January 2011. Retrieved 28 January 2011.
- "Serse Cosmi nuovo allenatore". US Lecce (in Italian). 4 December 2011. Retrieved 4 December 2011.
- "Trapani, Cosmi nuovo allenatore" (in Italian). La Gazzetta dello Sport. 11 March 2015. Retrieved 1 April 2015.
- "Serie B: Trapani sack Cosmi". Football Italia. 28 November 2016. Retrieved 14 January 2017.