The opening goal came in the 18th minute after Cassidy broke from an Athlone corner and fed Chris Mulhall on the right. His cross seemed to have too much on it but Conan Byrne controlled the ball superbly and set up Kevin Dawson for a tap-in.
On 66 minutes Shels pulled further ahead as the Athlone defence stood still, allowing Mulhall to steal the ball. Michael Schlingermann dived in, Mulhall tumbled and referee Darren Coombes pointed to the spot.
Philly Hughes stepped up and drilled in the penalty kick to leave Athlone dead and buried.
SHELBOURNE: Delany; Matthews, I Ryan, Paisley (Boyle 46), Fitzgerald; Byrne, Cassidy (Bermingham 71), Dawson, D McGill, Mulhall (Clancy 79); P Hughes.
ATHLONE TOWN: Schlingermann; Fallon, Danaher, Barrett (Relihan 67), Carr (Sweeney 84); J Hughes, Colbert, Dunne (Sherlock 46), D Ryan, Williamson; McGee.
Referee: Darren Coombes (Dublin).
LIMERICK FC overcame a strong second-half assault before eventually emerging with three valuable promotion points at Ferrycarrig Park last night.
Jeffrey Judge and Paudie Quinn put Limerick 2-0 up before the break but Youths got themselves back on level terms with two Ben Ryan goals.
However, just two minutes after Ryan’s equaliser Tom Elmes scored put through his own goal on 77 minutes to hand the visitors the points.
WEXFORD YOUTHS: P Holden, S Nolan, D Broaders, K Keogh, M Kehoe, P Malone (M Mullen 86), G Ylverton (R Vickers 78), C Wall, D Furlong, D Walshe, (T Elmes 55), B Ryan.
LIMERICK FC: B Ryan, A Banbarkar, B McCarthy, P Purcell, C Treacy, P White, D O’Leary, (G Coughlan 88), J Judge, P Quinn (T Lyons 82), P Hynes, S Brosnan (C Breen 70).
Referee: Keith Callanan (Cork).