There is growing societal pressure, expressed through government legislation and consumersâ€™ purchasing choices, to abolish livestock systems considered detrimental to farm animal welfare. Such systems include farrowing crates, which are behaviourally and physically restrictive for sows. Therefore, identifying less restrictive farrowing systems for commercial implementation has become an important focus of pig research. Despite numerous attempts to develop indoor alternatives to crates, there is as yet no universal acceptance of such systems at the commercial level. The primary concern is piglet survival, because often favourable figures are reported at the experimental level, but not replicated in commercial evaluation. Alternative farrowing systems should equal or surpass survival levels in conventional systems and perform consistently across a range of farm circumstances for widespread commercial implementation. In addition, it is important that alternatives consider ease of management, operator safety and economic sustainability. Utilising a large database of literature, 12 existing alternative indoor systems were identified and compared against each other, conventional crates and outdoor systems. An assessment of how well alternative systems satisfy the design criteria for meeting animalsâ€™ biological needs was carried out by developing a welfare design index (WDI). The physical and financial performance of these systems was also evaluated and summarised. The derived WDI yielded values of 0.95 for conventional crates, with higher scores for commercial outdoor systems of 1.10 and indoor group farrowing or multi-suckling systems (e.g. Thorstensson52.20). However, the high total piglet mortality (23.7%6s.e. 2.26) in indoor group systems compared with conventional crates (18.3%6s.e. 0.63) and outdoor systems (17.0%6s.e. 2.05), together with the added capital cost (92% more than conventional crates, 249% more than commercial outdoor huts), mainly as a result of extra building space provided per animal, question their feasibility to deliver from an economic perspective. Designed pen systems offered the best compromise, scoring 1.64 from the WDI, with a total piglet mortality of 16.6% (6s.e. 0.88) and capital costs and labour input more comparable to farrowing crates (17.5% more than crates). The critical review of different systems was hampered by the lack of comprehensive data and detailed system descriptions. When attempting to assess welfare and economic attributes of systems, there are certain caveats that require discussion, in particular weighting of the contribution of different design attributes to pig welfare, the relative importance of the sow and her piglets and the many potential confounding factors that arise. Also, when judging any system, it must be emphasised that the maternal characteristics of sows and the quality of stockpersonship will be integral to its success.