2011-12: Prior to her senior season on the Northwestern swimming and diving squad, ran for the first time as a varsity member of the NU women's cross country team in the fall ... Academic All-Big Ten ... Earned an NCAA `B' provisional qualifying time as a member of NU's 800 free relay at the eight-team TYR Invitational (11/19), swimming a 7:22.44 ... Ranked fifth in the 200 free on Northwestern's top times list for the season ... Competed individually at the Big Ten Championships in the 50 free (52nd), 200 free (57th) and 100 free (78th) ... Swam a career-best 52.40 in the 100 free during the prelims of NU's TYR Invite, eventually finishing 16th overall after swimming in the consolation final ... Also swam in the TYR consolation heat of the 200 free, placing 10th overall ... Qualified for the bonus final of the 200 fly at the TYR Invitational before coming in 22nd ... Best dual meet finishes on the year were a trio of third-place efforts, one in the 50 free against UIC and North Dakota (11/12) and two more in the 50 and 100 free events during NU's winter training trip dual against Colorado College and Austin College (12/17).
2010-11: Member of Northwestern's freestyle unit ... Ranked fourth in the 100 free and fifth in the 200 free on NU's top times list for the year ... Academic All-Big Ten ... Swam career-best times in the 100 free (41st) and 200 free (42nd) at the Big Ten Championships ... Also competed in the 200 fly (43rd) at the conference meet ... Qualified for the consolation final of the 200 fly at Northwestern's own six-team TYR Invitational (11/19-11/21), finishing 12th overall ... Won the bonus final of the 100 free at the TYR ... Best dual-meet finishes of the year were a fourth-place effort in the 200 fly at NU's quad dual (11/6) and another fourth-place result in the 200 free at Iowa (01/22) ... Also scored a dual-meet point by taking fifth in the 100 free against the Hawkeyes.
2009-10: Competed in the 200 fly, 200 free and 500 free at the Big Ten Championships ... Academic All-Big Ten ... Cut more than two seconds off her career-best time in the 200 free at the conference meet with a 1:51.45 ... Qualified for the consolation finals in the 200 fly, 500 free and 100 free at Northwestern's six-team TYR Invitational, winning the heat in the 100 free ... Her time of 5:00.83 in the 500 free was a then-career-best ... Also won the bonus final of the 200 free at the TYR Invite ... Best dual-meet finishes of the year were a fifth-place swim against Wisconsin in the 200 free (11/13) and a fifth-place effort in the 500 free versus Iowa (1/23) ... Swam a then-career-best 1:53.53 in the 200 free in a time trial during NU's meet with Iowa (1/23).
2008-09: NU freestyler ... Suffered a season-ending injury during winter break ... Had a sixth-place finish in the 500 free at the TYR Invitational ... Scored dual-meet points against Indiana (10/24) and Illinois-Chicago (11/15).
High School: All-American and Georgia state champion in the 200 free ... Scholastic all-American ... Atlanta Journal-ConstitutionAll-State team ... Earned Coach's Award and Most Dedicated swimmer honor for Marist swimming ... High school team is the defending state champion ... Swam 12 years with Dynamo Swim Club ... Short course national cut time in the 200 free ... Member of the Georgia Zone team in 2004-05 ... Carries a 4.0 GPA ... National Honor Society member ... Vice president of Mu Alpha Theta ... Latin Honor Society member ... Vice president of Fellowship of Christian Athletes (FCA) ... Eucharistic minister ... Member of Habitat for Humanity.
Personal: Born Sheila Irene O'Neill ... Daughter of Tom and Maura O'Neill ... Chose Northwestern over Harvard, Notre Dame and Princeton ... Majoring in mechanical engineering.
O'NEILL'S PERSONAL BESTS
| Event | Personal Best |
| 50 freestyle | 23.76 |
| 100 freestyle | 51.62 |
| 200 freestyle | 1:51.01 |
| 500 freestyle | 5:00.79 |
| 200 butterfly | 2:04.81 |